I am reading the theory stuff in Bristol on ATP digital everyone at our school got one and we had to pass all progress tests etc. to be allowed to take the exams. Its a lot of good theory there explaining how to calculate different things.
As for doing the exams you are allowed to pass as many as you manage each day, but I do not advise passing more than one except the comms since they are easy. The new thing is that you have to reserve for May and June or risk not being let in on an exam since they made a new system of reservation of examinations. But you can actually reserve and resign if you do not feel ready no one will force you to start your exam.
As for doing my exams I sit 14/7 each day and learn stuff ofc if I do not get 100 % on every try in aviation exam, bristol and atpl questions I will not start my 2nd session (In the first one I did General Navi, 2x comms and Human Performance). My plan is Radio Navigation, Instruments, Operational Procedures and Air Law in April, Principles of Flight, Planning, Performance and Mass and Balance in May, Airframes and systems + Meteorology in June. And 2 sessions in reserve just in case (plus eventually time in June to do an extra exam).
You do not have to worry cause if you start one session you do not have to do the next session in next month you got 18 months to pass everything. I try to do it quickly because if I manage to get done quickly I will be able to get all my licenses this year (MEP(L), ME/IR, CPL + FI ). But ofc. its more important to get first time passes so I will not go if I am not sure that I will pass. So then it will take more time if necessary. Just remember everyone learns theory in their own pace so everyone have to consider their own pace, since only you know how fast you can learn.