With most treble hook baits, the main thing you’ll want to pay attention to when selecting the size trebles to use is whether or not the hooks will be able to hang up on each other. There are more specific scenarios, like jerkbaits for instance, where you have to be careful not to put heavy hooks on the bait as that will mess up the bait’s ability to suspend.
But for the most part, you can pick trebles that can’t quite touch one another and this will max out the size possible for the bait. No. 4 trebles will do this for most half ounce lipless crankbaits and many squarebills. Going up a size to two No. 2 trebles works well for most walking-style topwaters between 4 to 5 inches in length.
There are also long- and short-shank hooks in both these two popular bends as well. You can use a long-shank treble to help a particular hook size cover more real estate. Sometimes you’ll want to use long-shank trebles with topwaters for instance, since the hook spacing is farther apart. Where you’ll use short-shank trebles on baits like squarebills, since the hook hangers are closer together.