I set up multiple profiles on different instances as there were quite a few downtime events when I started. Now things are a little more stable and I only use two. I wonder how much of that decline is from redundant profiles going dark without actually losing the user.
I chose mander.xyz and feddit.nl partially because neither require an email address. I haven’t really kept track of who all they have and have not defederated from. I think both don’t defederate much. I use the block feature in Connect liberally to remove the communities I don’t care to see, like the tankies.