Really, don’t sweat the assistance too much. Fit in in as you can and how your body and schedule will permit.
Do you know your schedule for a given week at the beginning of the week for how many days you will have to train? If so, I suggest something like this:
2 Days: day 1- squat/bench; day 2- deadlift press. Only do the assistance you have time and energy for. If a third day magically appears, do more assistance then if you want to.
3 Days: day 1- squat; day 2- bench/press; day 3- deadlift. You should have time on these days to fit in your assistance. Ideally it would be great to not have these three days consecutively without rest, but we do what we have to do when work/life schedules get crazy.
4 Days: day 1- squat; day 2- bench; day 3-deadlift; day 4- press. Again, you should have time and energy to do the assistance here, but again be mindful of trying to get a rest day in without training 3-4 days in a row.
I wouldn’t schedule a third day to just do assistance work. I suggest a third day of assistance only if you’re schedule is unpredictable and you know you only have two guaranteed days to do the main lifts. In that case if a third day pops up you can use it for assistance and you’ve still done your main lifts. But if you know at the beginning of a week that you will have 3 days to train, split it up so you do a main lift(or two) each day you train. I hope you understand the difference.
Again, don’t sweat the details on the assistance stuff too much. If your body can handle 100 chins after doing a workout and it doesn’t hurt your recovery, go ahead and do it. If you can only do 25 good chins after a hard workout before your form goes to crap and you start kipping around, only do 25 (or take longer rests if that’s an option.) Your main focus, especially if you have a crazy schedule, is to get the main lifts in and then the supplemental work. Whatever assistance you manage to get in after that is a bonus, and good on you for finding a way to knock it out. Do what your body can handle, what time permits, and what you can recover from.
And I personally discourage training deadlift as a main and supplemental lift twice in one week. That seems like a lot to try to recover from.