I'm about to commit what is probably analytics heresy: I'm going to give a subjective impression without collecting data (because I'm too lazy to do so).
I frequently hibernate my Linux Mint desktop rather than doing a full shutdown, just to save time both when I'm done for the day and when I'm resuming the next day. Both hibernation and wake-up seem to take progressively longer as the time between full boots increases. I notice this more if I've been using the NetBeans IDE for coding, to the point that I'll occasionally do a full restart just to make hibernation cycles go faster.
Looking for a way to speed things up, I found µswsusp (userspace software suspend -- I'm not sure why they want to start with a "mu", but for free software I'll forgive the occasional bit of fluff) and a very clear and helpful HOWTO. (Update: The HOWTO may have disappeared -- at least I can't get to it at the moment -- so here is an alternative source. Check the comment on Aug. 16, 2012.) I installed the small package from the Canonical repository, added the 00sleep_module file, and hibernated. Hibernation and reanimation both seem notably faster. Some of this may be the result of a percentage progress measure being displayed, but I think there is a real difference in both directions.