I spent 2 days messing and manually retuning last year..
We're in a marginal area between multiple transmitters with hugely different changeover dates.
The main one is Crystal Palace which was almost last and has just switched.
After an aerial upgrade some considerable time ago now (the old one was pretty tatty anyway) which just made things worse by picking up more marginal signals I decided to go for FreeSat when it appeared and had "stabilised".
Did the same (as I've said before) for my in-laws too, as they are in another marginal location.
It's worked brilliantly.
(trying not to sound smug)
I still retune our Freeview TV's and boxes but the mish-mash of stations, many appearing 3 or 4 times, is just ridiculous.
The whole system is not thought through properly, though I gather you can now buy tuners where you can specify your "region" and cut out all the carp...