It depends on what you are doing.

If you are converting a home DL to a Chinese one, it only requires two visits to the foreigners' TMB (open late each evening, and also on Saturdays):

1) one visit to hand in all your paperwork (including completed medical form) and (assuming all the paperwork is in order) schedule the computer test (I recently heard there was a 3 week waiting period); and,
2) one visit to do the test (assuming you pass)

I don't think you need that new, second exam for a DL conversion? Someone may correct me on that one. Since Jan 1, 2013, things are somewhat different.

If, however, you are taking the entire course for a motorcycle license (e.g., at Laoshan), the course itself (and road test) is one week (5 working days). In addition, you have two written exams that are scheduled beforehand.

I've heard that there is about a 3 month waiting period to get into Laoshan. Well, there is for an E -> D conversion.