I'm going to chime in here and offer my perspective on crashes as a non-drumming musician. My main instrument is trumpet, so sometimes I have a perspective about how drumming relates that's a bit different than someone who only drums.
Crashing is about punctuation in phrasing. Sometimes it's intuitive, such as crashing the "1" every 4 or 8 bars - typically to punctuate or delineate a shift point in the music, i.e., opening verse to mid-verse, beginning of the chorus, beginning of the bridge, etc, depending on song structure of course - sometimes a re-intro into a song will be 10 measures, but the concept is the same - a crash on beat "1" of the verse is the line of demarcation between the sections of the song.
Then there are hits, punches, or whatever other term you want to use, where the crash is adding punctuation to a musical point within a phrase. Often we use smaller faster crashes or splash cymbals for these.
Start thinking like a singer, guitar player or horn player, and start digging into the phrases of the music you are listening to, and see if you can find patters for the how/why a player crashes. Some drummers crash all over the place, some are a bit more minimalist in their approach, but usually the hits, punches and crashes make sense from a phrasing perspective, and they will help you in your own efforts at crafting drum parts that make sense musically.