I'm not seeing many (any?) crashes, and I don't know that I've had to rebuild my Aperture database once since I started using it in late 2006.
So I suspect there's something else going on with your system.
I've had to rebuild my Library twice this week, something in all the years of using Aperture I can't remember ever doing. My computer just freezes ( a 2012 MBP), I have to power down. I suspect it might be something to do with Spotify, that's the only change I can think has been made recently.
To play it safe I've just ordered another backup drive I'm going to copy the library to. This will be a Thunderbolt not usb, just incase there is some problem there. Another copy (I have 2 copies already) will not be a mistake and a move to Thunderbolt should be a nice upgrade. Still not sure why the computer freezes.