There seem to be big differences in CLA's.

The repairers I use send back shutters with accurate speeds whereas some (reputable) US repairers send shutters back with comparison charts - actual shutter speed as opposed to marked speed, I'm talking about way outside the +/- 30%, the price is quite a lot lower though in the US for that CLA.

the UK CLA's I' had are more ln the region of +/- 10% which is acceptable.