I purge continually - things that the fit isn't quite right, or they're annoying in some way, or I've fallen out of love with them, or they don't work somehow the way they were intended in outfits. I rarely wear things out (I'm good at careful laundering, but also quite fickle)

I keep a donation bag to add to at all times.

Often I put a piece in my pile to be altered/repurposed by me. After 6-12 months, it typically goes into the donation bag.

I do keep a holding place for the 'maybe's that are getting ignored -- probably because of one of those reasons I listed, but I'm not quite ready to let go. Next time I'm in a mood to consign, I grab that batch. I don't think I've ever regretted when I finally let go!