The main problem is actually scheduling for now. And VFR delays caused by weather, but IFR is totally about planning. Because math is simple. For example they 4 IFR a/c with 5 IRI. They trying to give every student 3 slots per week.
A/C can operate 9 hours a day roughly. Because of ATC working times. And yet of course its impossible to get 9 hours because of refuel and so on... So in 6 working days (because one day off for instructor) if we calculate from 7 hour average, 168 hours. 3 slots per week for a student means between 9-12 hours (because of some flights 2 hours some of 3 hours and some 4 hours. But actually majority of flights 3-4 hours). So if we calculate from average 11 hours they need to operate 16 students in one time.
If you will look at amount of student they try to operate for now around 25-26 students at one time. And yet this is not only problem. Because of 100h-200h inspections most of the time they have 3 even sometimes they have 2 a/c. Even not talking about unexpected maintenance for a/c. And yet they doing all of this in other base with third part company.