Whats better: 1 share per TM backup, or one big share for all TMs?

My question is one of best practice and pros and cons in using Drobo FS as a Time Machine backup for multiple Macs.

Should I create 1 share per mac, or 1 big share to fit all my macs’ info?

Is there any trade off to one way or the other?

I created one share per Mac as I can limit the size for each backup individually.
Imagine a large Time Machine history of one Mac and a short history of another Mac on a single share. If the share get’s full within a backup to the “short history” Mac, Time Machine has to try to reduce the short history even more.
When defining individual shares by size (harddisk size * 2) you will get the same “granularity” of the backups for each Mac.

I don’t think there is any downside of creating the separate shares. The Time Machine capable shares are still thin-provisioned like all the shares are, so they only consume the space they need.