because mine is now needing…
As determined by?
Is there play/knocking? Very stiff to move? Or are they just ‘not as smooth as they could be’?
I don’t know if you do your own maintenance or take it to an LBS, but what I would tolerate and keep an eye on on my own bike an LBS might advise a customer to replace, especially if they only see said customer infrequently and the bike is in for other work at the same time.
Also, frame bearings are an unusual case, a normal cartridge bearing is actually ill suited to the job (low speed, partial rotation, high load) so they can wear in funny ways, and often if off the shelf bearings are used they are woefully under-lubed for use on a bike in the filth and (relative) static conditions they operate in.
Normally they end up needing replacement due to corrosion or premature wear caused by dirt/water ingress rather than actually ‘wearing out’ if you know what I mean, if you can prevent the corrosion or contamination then they will often last a lot better.
A good purge and fill with a proper (and proper amount) of waterproof grease can actually make them last many times longer than they would if just fitted as they come. My record is ~7 years* out of a set on a Mk1 Intense tracer, which I bought second hand, and eventually sold on with the same bearings, and that’s a bike that was known for ‘eating bearings’ at the time.
*used summer and winter and for quite a few XC and 24/12hr races.