Depends
Also you never know when you'll need to borrow buses back. One thing that does surprise me is the reluctance to utilise the notts and derby fleet at Derby, especially when it's mainly ex trentbarton vehicles.
There were a few weeks when red solos would work for notts and derby one day and Trent the next, doesn't seem to happen now though.
They seem to simply not have enough spare buses, at Derby at least, which is why they miss out several services on a daily basis. It appears to be because on paper they think they should have enough spare buses, and the fact that the reality doesn't reflect this seems not to matter.
Part of the problem may be that the fleet is older (on average) than it has been in previous years, due to a gap in investment during covid, or they simply can't cope with the volume of maintenance at Derby. Either way it has been an ongoing issue that hasn't been resolved.
I wouldn't be surprised to see a modern maintenance facility built on the notts and Derby site, especially if any funding is forthcoming for electric buses and infrastructure.