when local DC agencies got busted by Feds. They had my number as I was their regular client.

Your hobby phone is not a pair of dirty underwear that you have to change every day. I wouldn't change it unless there is a good reason to change.

I have a shortlist that I keep, and would hate to go back and give them my new number every few months.

That being said, do what suits you.

As an escort i use a nontracable phone but forgive my ignorance... what is the purpose of the hobby guy switching/ dumping the phone so often. I thought the main purpose was to offer anonymity but if there other benefits please educated me

I think you watched too much 24.

Assuming that you aren't a terrorist or a hit man, this is extreme overkill.

It's your own comfort, and you can do whatever you like, but if you hobby phone is a burner, I don't see the need to dump it until it becomes a problem.  LE isn't tracking you.  They aren't going after random hobbyists, and even if they were, the phone isn't how they'd catch you.  

I'll dump mine when I see the number published somewhere, or when I start receiving harassing calls that I can't block with google voice.

I use my cell.  I'm not paranoid.