I normally change mine each year, and always the complete set regardless of wear or use (though perhaps not after last year )
Lamkin Crossline Jumbo's for me
MCC+4 for me.
Normally I'd change them all at the beginning of the year, but gave them all a wash the other day and they're almost like new.
Very important for me is what they're like when wet as I struggled for years, with the MacWets these are awesome so won't be changing.