Unless you have zero target panic or shooting issues, shooting multiple bows and making changes is a hindrance. It's hard to keep good control if you aren't sure your bow is doing what you expect. Multiple bows when you aren't sure about the setup can cause you to anticipate the shot ie target panic.
That being said, when I shot competitively at a national level, I always had at least two target bows and at least two 3 D bows. Granted, I was sponsored, and literally could build a bow, tune it, and win the local 3D tournaments on the weekend.
That being said, I think everyone needs a backup bow, release, arrows, sights, etc no matter if you hunt, shoot targets, or shoot 3D. They don't have to be identical, but something that you have confidence in would be very helpful if you have an unexpected failure/breakage, or just to confirm it's the bow and not you.