philspace:
as far as I know the Olympic course, Merion and Royal St Annes & Lytham all are rather short courses under 7,000 yards.
Wiki (not the most reliable source, I know) has Olympic at 6,948 yards, Lytham at 7,118 yards and Merion at 6,842 yards although I suspect all three courses may be lengthened for the Opens. As for shorter courses holding up, StA plays just 6,721 yards so it's not as much in the length of the course as how it's set up.
Jack.