I love Machine, so no matter what other weapons I try, I know I'm good with Machine, and that I love that weapon, but there are times where I want to do well with a weapon and Machine is not doing it for me, so I try weapons that are considered good, and try to put time into them, sometimes it's weapons I just like or always wanted to get into like Octobrush or Foil Flingza.
Since I've done this for a long while, I already have practice in weapons that are a bit harder to get into like Stamper, Slosher or Splat Dualies, and when I feel like they don't work because I'm having a hard time playing them well, I can just try another weapon I feel it's easier on me like range blaster, or a shooter like 96 deco or 52.
At the end of this, I can give myself an idea of what weapons I do well with, and what my peak might look like with them if I play with enough consistency, still on the process of choosing another weapon to heavily dedicate to, but I think trying out weapons for extended periods of time is fun, and you might find a real good weapon there :]