I am living in the hell that is 'cleaning up old backups', which is pathetic and disgraceful and slows stuff down to a grind. I want to tell Time Machine to actively delete all backups older than 3 months, and do it once and for all. I'd also like for Time Machine to keep that as a default rather than having to do that by hand myself all the time. How do I do that? I am not after suggestions of 'open time machine, find old backups by hand, bla bla bla'. It is a computer. I should not need to prune backups by hand or enforce backup rules by hand.

I am cleaning up old Time Machine backups, which slows stuff down to a grind. I want to tell Time Machine to delete all backups older than 3 months. I'd also like for Time Machine to keep that as a default rather than having to do that by hand myself each time. How do I do that?