"you [have] to leave a little play in the bearings. As you tighten the QR that play gets tightened up."
From one of the OP's other threads, there is an implication that they tighten the QR skewer by (just) turning the QR lever. I asked but no answer forthcoming.
"Obviously you took the bearings out both sides, but did you undo both cones or just one side? One side shouldn't cause you any problem, taking both cones off risks them being slightly out of place when you reassemble."
OP has said they "[took] everything apart in one go I'm sure I took the bearing from both sides out axel [sic] the lot". But with everything (including washers/spacers) where the hub ends up on the axle doesn't make a difference to the distance the smallest sprocket is from the RH dropout (to which the RD is fastened). The RH locknut is still hard up against the dropout. Would make a difference to whether the wheel/tyre is centred in the frame.
"In 40 plus years of cycling and DIY ING bikes, I've never had to touch the limit screws on a bike, ever. They're set perfect at the factory and I assume unless you replace an derailleur...you never really would have to adjust them."
This is not my (or I expect most chatters') experience: you have led a charmed (limit screw) life. When, during that 40+ years, you "replaced a derailleur" did you not have to adjust ("touch") the limit screws?
How can 'the factory' know what speed cassette an RD will be used for? (width of cassette differs)?
https://bike.bikegremlin.com/3573/bicycle-cassette-rear-chainrings-standards/
https://sheldonbrown.com/cribsheet-spacing.html