Some might die but for most the the part with the clitellum (band in the middle) will live on and grow back. If you were chopping them up on a daily basis I'd say stop, all that work for no benefit.

Since those worms are there naturally I wouldn't worry about bisecting a few now and then. Those are likely Anecic worms or worms that live in the soil and come to the surface to eat. They go back down and poop in the soil distributing organic material so they are nice to have. Even if you removed all of the ones you find and squish them I'd bet you'd find more move in eventually, provided there is decaying organic material there for them to chew on.

Go ahead and work the soil in your beds, I don't think you are doing them (in a wider general sense) any harm. A few that you chop up might disagree but hey, who's the big dog in your ecosystem?

I just saw the biggest worm! It had to be 9 or 10" long and 1/2" thick!

No wonder there are more robins this year than I've ever seen before.