The Test at a Glance doc for 5152, 5153, 5154, and 5155 (http://www.ets.org/s/praxis/pdf/5152.pdf
) indicates that
- 5152 is 3.5 hours (which is 210 minutes) and 210 multiple choice questions; that's a minute per question
- Each of 5153 (pedagogy), 5154 (English/social studies), and 5155 (science/math) is 70 minutes and 70 questions, which is also a minute per question
In other words, one has the same amount of time per question whether one takes 5152 in one long go or whether one spreads it out over 5153, 5154, and 5155 (which could probably be scheduled on different days). Other things being equal, for nervous takers of 5152 it probably makes more sense to spend the inevitable additional money and go with the 5153/5154/5155 package, spread out so that one isn't having to prepare all that material all at the same time.
Test 5156 (PA middle school English) has its own Test at a Glance doc (http://www.ets.org/s/praxis/pdf/5156.pdf);
this is a 90-minute test with 90 multiple choice questions, so again we're dealing with one question per minute. I infer that 5157, 5158, and 5159 (which cover social studies, math, and science - I don't know which is which) are structured similarly. Clearly there are many more questions in each subject area - though the upside of these tests is that one schedules them separately, so one isn't having to prepare for English AND social studies in one go, and the upside of more questions is that one can get a greater number wrong without being sunk.