In theory, it should be shorter and in any case take less than four months because there is an implicit refusal after four months. But as you have seen the first time around, there is a huge gap between theory and practice and this four-month rule is routinely ignored. The time it takes also depends a lot on the place where you live (i.e. whether the préfecture is overloaded or not) and possibly on your exact status (student, vie privée et familiale, etc.).
Worse case I have personally heard about was over 9 months, which means living most of the time with a récépissé but no valid carte de séjour since you have to start all over again a couple of months after getting the new carte de séjour because, as you already noticed, its validity period always starts on the date of your application even if you get it many months later. That was in Seine-Saint-Denis, which is notorious for its poor treatment of foreign residents. But I also know people who got theirs in one month (in Meurthe-et-Moselle for example).
But there is one big difference between the first application and renewals: You are allowed to leave France and reenter with a récépissé for a renewal (together with the expired carte de séjour), see this question on the travel website.
