Tom - Bill has given you the answer. I knew there were lots of sprinkler-heads/yardage markers but the reason i was a little unsure because I don't think I can ever recall seeing a sprinkler on at Hoylake, so I was a bit unsure about their purpose! And the fact that they clearly did not water the fairways despite extreme weather in July only added to my uncertainty!
Mark - I did not actually play the course in July so can't give you a complete answer. For someone of my skillset - long-hitter, dodgy short game - I am sure July was harder than October! But I would have enjoyed the variety. The punchbowl hole, for example, is driveable, possibly even from back tees, when the ball is running, but when we played it and the wind was out of the north, even your best drive could not clear the big hill in the middle of the fairway.