What specific maps/runs made you improve at a particular skill, game situation, or understanding?

I'll go first by mentioning some examples of runs that I believe made be better with particular weapons (partly inspired by a comment Looper made about av29m being a run that made him get good with BFG).

- E1M2 max made me better with chaingun. Most of my runs up until this point hadn't involved the chaingun very much or at all aside from mowing down a horde of fodder or sniping down some hard-to-hit monsters, or shoot switches. This run however is almost exclusively chaingunning monsters low-tiers, and the tight time frame to crack record on it forces you to chaingun as effectively as you can. Essentially what I came to an understanding and grasp of is that it is much better to tap chaingun in an optimized-chaingun max like this, as you still maintain a high rate of fire except with 100% accuracy. Once I began doing this my hit-rate on enemies went up a lot and they died quicker with less ammo taken.

- lv02m made be better with SSG and lineups. It also made be a little better with shotgun, as did ev01m, pl01m, and E1M5 max, but the principles you apply with SSG are similar as with shotgun in my opinion. Since lv02m is predominately an SSGfest on low-tiers with an extremely tight time barrier, there are a lot of lineups required to cut down the numbers with minimal shots taken. After playing the map 35k+ times, I now instinctively and automatically hunt for lineups with SSG (and SG) and it would actually take a bit of cognitive effort to prevent myself from hunting lineups now lol. Lineups in general can also be helpful for provoking infighting, so lineups are super effective for optimizing in maxing. Additionally, lv02m made me think about the spread of SSG and manipulating how it changes with distance and enemy configurations. Sometimes you may get a lineup of fodder...except it's not enemies behind one another in front of you, it's enemies linked across your field of view in a chain as if they're holding hands...in other words, it's a horizontal lineup you're staring at. In cases like these with a horizontal line of fodder (2-3), it can be advantageous to try to back up away from them and then shoot with SSG, as you get more horizontal spread this way (although if you have the time, it may be smarter to run to the line's side to change the horizontal lineup to a traditional "downhill" one). I believe I got the idea to shoot this way in such circumstances from one of looper's lv02 demos.

- Sunlust D2All Max got me better with implementing SR50. Mostly, needing to setup the death-skip in Map10 via a lineskip forced me to make my strafe-divisor really high to make VMM work so I could perform the trick, so consequently I needed to actually bind a setup to use 4-key SR50 instead of mouse SR50. It's hard not to SR50 in every open area I see now

- poog31m made me better with rocket launcher. I think I was already pretty familiar with optimizing rocket splash from previous runs, probably a run like su19m, but this map has several fights that you can't really beat unless you are optimizing your rocket splash. The caco wave in the 2nd main room mandates it with my strategy, and the 2nd secret room's first fight also mandates it practically.

- sc31o made me come to an understanding that movement players are insane at movement. For me, I hadn't really tried to perfect movement from point A to B in a run before, and I didn't think it would be that bad having seen the demos of movement players, because unless you've tried a movement run before it really doesn't look like a movement player is doing much in a demo. It's "just" SR50ing on the shortest path to and around corners and backing up from doors and SR50ing through them at the right time. I found it very tough transitioning between SR50s and turns, and also getting the best lines and angles was tough too, frustrating most of all, and that's why I'm not a movement runner.

What runs made you good at rocketjumps? What runs turned you into a glide addict/good at fitting through while sucking in your gut and holding your breath? Runs that improved how you develop routes for maps? Runs that got you better at dealing with archviles, archvile hordes, cybers, cyber hordes, dimensions map03 references? Runs that improved your punching prowess? Runs that improved your movement? Runs that developed your avj skills? Runs that changed how you regularly diagnose monster priority? Runs that taught you how to zero press or void glide? Runs that taught you you don't need to have 200/200 and 600 cells at the end of every map in a movie run? Runs that just generally changed your perspective on speedrunning the game?

Please comment, because this subforum is basically dead.

Whilst not a demo, just a whole mapset, Junk Food 2 specifically made me get a whole lot better at using BFG tracers more efficiently to clean up large crowds quicker. This is something that I feel I improved upon further when doing Resurgence Map 32 max attempts. 

Speaking of larger maps with higher kill counts, Judgment Map 27 and Map 29 max definitely helped me to improve my routing of larger non-linear maps. Whilst Judgment Map 26 and Back to Saturn X: Episode One - Map 24 helped me with routing large linear maps I think my love for doing maxes on these kinds of maps stemmed from these maps specifically. Not only this, but it helped to build my endurance when doing these longer runs so I'm not getting tired halfway through a run and losing focus, doing dumb mistakes and losing time. I still get a little tired during longer demos, my Altitude run is proof of that because I messed up my route, but not as much as I probably would have if I hadn't done as many long maxes before. 

I'd never thought I would credit the master levels for anything but Canyon made me a little better at doing quick glides in runs. I utilise an east glide at the start of the run in order to open up the secrets that would usually not open until the end of the map, saving quite a bit of backtracking. 

In terms of dealing with Cyberdemons, I think I'd probably say Plutonia 2, either Map 32 or the D2All attempts from 2022 and early 2023 helped. But in tight spaces, I'd probably say the Abyssion max since it often pits you against Cyberdemons in tight areas and no BFG until the end. 

I wouldn't say my movement is top-tier but doing UV-Speed and NM-Speed demos for the Master Levels early on definitely helped to boost it up a bit to being decent rather than utterly trash. 

And finally, Speed of Doom Map 14 pacifist probably helped in some way with navigating through large crowds of enemies, especially at the start and end of that run.