It's a bit low tech - I took a pen and notepad and went through the most recent rated games whereby tyrell won BEFORE turn 10 - ie with 7 Castles.
Max turns 9 was the best filter I could come up with for 7 Castle only wins.
Secondly the sample size is rather small - 50 games but this already took a couple of hours so...
Lastly tides of battle games are included as well - again I didn't know how to filter them out so this is by no means exhaustive.
Without further ado here are the castles:
Highgarden and oldtown 50/50 - 100%
The reach 40/50 - 80%
Starfall 30/50 - 60%
Flints finger 22/50 - 44%
Yronwood 20/50 - 40%
Pyke 18/50 - 36%
Riverrun 17/50 - 34%
Sunspear 15/50 - 30%
Seagard 14/50 - 28%
Storms end 13/50 - 26%
Lannisport 12/50 - 24%
King's landing 11/50 - 22%
Harrenhal 10/50 - 20%
Crackclaw point & winterfel 6/50 - 12%
Moat cailin 5/50 - 10%
White Harbour 4/50 - 8%
This post is dedicated to ser hodor whose work has helped me become a much better player.
Some early observations...sniping Starfall is legit and highly recommended even if your dornish ambition goes no further.
Sunspear and storms end go hand in hand.
Flints finger is tyrells 5th best castle!
There is a big dropoff between taking Starfall only, yronwood as well and sunspear on top of it all. How deep should your dornish invasion go?
Conquering either greyjoy or martell seems to be the way forward! Don't try to take the eyrie.
1st and last games analysed were (ref) 261636 and 253440