Single Status Update
Yo!!!! Your quest to play EVERY Maximum Doom level is admirable, if slightly insane, but I must tell you about some of the things I learned from plowing through it myself.
Firstly, you really do need to know the amount of maps in each given wad before playing it. I see that the engine you are playing through lists the number of maps in each PWAD, it's very important to always check this - in your last video, you played the first level of EP.WAD and quit out before loading up the next map. This is actually a nine-level wad with a secret level, so playing through the whole thing is a bit of bastard -Spoiler
The secret level is in map 6 - there are two exit buttons (in the dark) next to each other, one goes to map 7 and one to map 9. With me so far? Then in the secret level, the exit room ALSO has two buttons, one is ANOTHER secret level switch, so it loops back to the start of level 9 again (for whatever the hell reason), and the other takes you back to level 4, which is the set level that secret levels progress to in episode 1. This is even before mentioning that this exit room is behind a false wall, and has a spider mastermind in it, so good luck with that (I, of course, was on God Mode).
My point is that to completely play this WAD all the way through without cheating will require you to play levels 4, 5 and 6 twice. I would also like to point out that this WAD totally sucks and I hate it with venom.
EDIT: Whoops, there's a secret exit button in map 3 as well. Disregard
WADS with this particular type of secret level crap are actually quite rare, as far as I remember - if they are created by one or two people, and made specifically as an 'episode replacement', usually they have taken care with the secret levels. The ones you need to look out for are the compilations, or 'wad packs' - unrelated levels put together by somebody and chucked on the 'net - there are LOADS of these in Max Doom. What you need to check is if the WAD contains a ninth, eighteenth, or twenty-seventh level, as these most likely won't be accessible at all through regular sequential play.
Which is why I would highly recommend considering using the IDCLEV level warp 'cheat' in these situations. I don't know if you would consider it cheating, but really, there will be no other way to play them (except for starting on these levels through the Doom engine you're playing through).
Also, the Doom Wad Archive (https://www.wad-archive.com/) is absolutely essential for getting info on Max Doom levels. Only a fraction of the WADs in Max Doom have accompanying text files, and this site easily allows you to look up info on just about all of them, not to mention pictures of the full automaps of the levels. This site is a massive help.
And for what it's worth, here's my Maximum Doom list that I did over a few years, basically scattered observations of my experience. I dunno if it's of any use to you, but it may be good for a laugh or two.
Okay, so keep up the good work, and I eagerly await your upcoming episodes!!!
D'OH!!!!!!!! I just looked up Zombotron's playthrough of EP.WAD, and I just saw that there is an exit switch to the secret level in level 3. Just remember to press the LEFT switch, that will take you to map 9, and then in map 6, press the RIGHT switch, that will take you to map 7. I should have known, but I'll be damned if I'm gonna play this bastard again. There may be other secret exit switches in the other levels as well, just lettin' you know.
Also, in map 8 there's a dumb trick you'll see every now and then - the exit switch has three single-use teleporter linedefs in front of it. Meaning, you'll have to approach it then get teleported elsewhere in the level three times before you can hit the switch. Again, this wad sucks.