I did the ATPL(A) theory exams in 4 sittings also doing it 4 - 4 - 3 - 3 with first time pass and about 92 % average, never heard anyone say or write about some higher requirements than 4 sittings, first time pass and above 90 % average. Studying for real I did between March and July (last session in the beginning of July and did not sit in May session). I believe its more important to learn the important stuff from the pure theoretical exams so you can explain it on the assessment than to pass as quickly as possible. While exams with calculations like General Navigation, Mass&Balance, Performance and part of Planning have to be learned then it can be easy to rely on question banks for a lot of the other exams.
Questionbanks are very good but only when not forgetting to learn for real the important stuff (assessor will probably not ask about when mosquitoes are active or that nickel-cadmium battery got Potassium Hydroxide electrolyte) in for example Operational Procedures, Meteorology or Radio Navigation. Since I believe the technical questions on the assessment if answered wrong when having high scores from the exams would make the assessor think the person just memorized everything and do not understand it. After all its about passing the assessment and not only getting an invitation.