Thank you! I didn't know that easy way to reply.
The compiler does some incremental compilation for the generated object files, so compile times are kept relatively small. Other than that, I don't think it makes a big difference for a developer except saving compile times. On the other hand, in this way you can't have a compiled library conflict so you have to "clean and rebuild" when this happens.
For example in Ruby there's no such thing as pre-compiling a gem, and every time you run an app the whole app is "analyzed" (parsed and converted to VM instructions), and so you can think in Crystal it's the same (except that it's compiled to native code)