Are you into speedrunning, and which categories do you favor?
For myself, I’m a SM-Max person – that is: wand start, Smite Master difficulty (skill 4), with all monsters dead and all secrets collected.
These are my current times. I am confident these *can* be beaten 😉
E1M1 – 5:12
E1M2 – 9:46
E1M3 – 10:29
E1M4 – 6:30
E1M5 – 11:16
E1M6 – 14:42
E1M7 – 13:10
E1M8 – 5:26
E1M9 – 12:09
Also check out the Heretic DSDA speedrun archive for world records. You can download the runs as LMP demo files, for local playback.
(Yes Heretic, like Doom, can record gameplay to file! Use the -playdemo command line argument, requires a vanilla compat port or the original DOS version)
https://dsdarchive.com/wads/heretic (use the “Map Select” link above the table to drill into each episode)