I am often surprised by the differences between people. Our likes and dislikes are affected by our physical and emotional states, either temporary or permanent and has brought me to the conclusion that if we all liked the same thing, there'd be one heck of a queue for what we like.
I haven't counted rides for a good few years now but I'd say these are the top 3 I've done in a day.
Nemesis: Back when it had single rider and it was right next to the exit. It never had a queue and most of the time you got on the same train you came off if you were quick enough. Used to love lapping this.
Inferno: On a very empty annual pass day a good few years ago we stayed on this for an afternoon. No idea on a number but easily 20+
Stealth: Quite a few times last year on offpeak weekdays they just left the gate in the station open so you could re-ride, most of the time getting on the train in front. Unsure on ride counts but easily 20+ a couple of times.
I've also rode Slammer for pretty much a whole day before but wouldn't have been a high ridecount due to how long it took to load. Used to do Detonator quite a bit in a day too.
They do yes. I find Thorpe are definitely the most lenient with re-rides out of the merlin parks. Alton isn't even worth asking.