I've been making trackers like that since I was a kid. The trick with things like that is that it doesn't help if players forget to use them. Some of them have those O's on their sheets already (I didn't even have to suggest it, it's just that obvious). Doesn't do much if the player gets so excited about resolving their ability that they forget to tick the tracker. I've never had issues with them tracking HP. I've had some issues with them tracking XP though. So I'm essentially certain that it's not a matter of cheating, merely carelessness.
As I said before, this is a friendly game amongst co-workers. For about half the group it's their first time playing 5e, and for the rest it's their first time with a TTRPG. I want them to get bitten by the bug. I don't want the game to devolve into me nagging them like their mother every two seconds, because I don't feel like that's the best way to hook a newbie with lifelong love for the game. Good table practices are something that can be taught down the line. Love for the game cannot. IMO that initial spark is better struck with fun than accounting. I've seen more than one DM lose a new player because they were more focused on 'playing the right way' than whether that player was actually enjoying themselves.
Hence, my approach. Perhaps you disagree and feel that accounting is the most fun you can have under the sun. That's fine. However, this is my group to run and I'm doing things my way. All I said was that I sometimes have trouble getting through more than one encounter in a session. Not all the time. There have been sessions where the newbies were on point and we got through 3-5 encounters in a single 3-4 hour session, along with a decent amount of role play. Not every session is like that, but I didn't phrase my post as a cry for help and thank you, but I don't need your help to 'fix' my game because it isn't broken. I said was that it would be nice if there were guidelines for building encounters for adventuring days meant to have only 1-2 encounters, for those times when that's what I want to run.
I dont get how they 'forget' to use them.
Remind them to do so. Heck, politely
order them to do so. After each ability usage ask them to 'tick it off the list'.
It's like someone 'forgetting' to write down the damage they've just taken or something. Surely you ensure they record that right?
Do they forget to write down XP and magic items they find as well?
I do character sheet audits on my players. If I cant read something on the sheet it defaults to the worst possible thing (
contra proforentum). If a magic item is duplicated in the party because someone forgot to rub it out when he gave it to someone else, it gets stolen by thieves. If a player has tracked encumbrance badly (or not at all) he can deal with a few levels of exhaustion that session (from a sore back). If a player forgets to note resource usage (ticking off slots or rages etc) then I assume the worst, and they're 'out' of that resource for the session.
Its a policy of strict liability. I have a lot going on as DM (statting up encounters, planning adventures and hooks, policing the adventuring day, running NPCs, making rulings, tracking several monsters HP and so forth) to have to worry that the players arent recording their own stuff.
Also, award inspiration or some other bennie for keeping accurate records, and a legible character sheet. You catch more flies with honey than you do with vinegar and all that.
Step one, you establish expected behavior at session zero (or before the session starts). Step two, you move to gentle reminders, and step three you politely order them to conform. Step four is when negative consequences flow.
The main point, is it's your table and your game. Set down the rules, and enforce them.