I really don't know, it seems so different from one time to another and from one kid and another...
For us, sleep disturbance last (usually) a couple of weeks now. Sleep needs did not really changed since he dropped the nap and he was on 11 h night on average (after one or two months at 11.5h), but rather fluctuate quite a bit: there are periods of 10.5 h followed by periods of 11.5 h. These periods seem to go in clusters, so nights are quite consistently the same length for a while, then shorten or lengthen for another while.