While I have some exceptions, I am satisfied with one recording of a work.
Time on this earth and money (but mostly time) are also factors.
If your collection is so large that you cannot listen to all the recordings within a year (not to mention repeated listening) I feel it is too much music.
Very reasonable.
I'd argue that as long as it is theoretically possible to play all recordings within one year (i.e. playing time < 8760 hours) it's o.k.
It's cheating of course because one has to sleep, but even 16 hours/day gives almost 6000 hours (corresponding to roughly 6000 CDs, I think I am still a little bit below that). Admittedly a more realistic value for listening is probably 20 discs per week (2 each workday and 10 on the weekend and holidays), giving around 1000 discs.
I once estimated that around 1000 discs would be the minimum for me if I wanted to own all the music important to me. Of course this was before the age of streaming and youtube. (But I think this is also cheating a bit. One cannot simply assume that these options will always be possible, we only needed a historically small relapse to the technical infrastructure of 25 year ago to render youtube and streaming almost impossible.)
