In a comfortable glider (both physically and mentally comfortable),
there really isn't much difference between 3 and 6 hours. In fact,
after an undercalled task, landing after only 3 hours sometimes seems
like a relight! Compared to long flights in power planes (boooring,
unless at 500 ft and 500 knots, or 100 ft and 100 knots), it always
amazes me how fast 6 hours can go by on a really fun (fast, high, low
stress) soaring flight.

On the other hand, anything over an hour in an uncomfortable
(physically) glider is torture. I really enjoy flying 1-26s, but
almost all the ones I've flown have been rentals and none have fit very
well - so there was never any problem in deciding to land after an hour
or two.

Water? Because it feels so goood! Like a big heavy Cadillac, cruising
along nice and fast...and faster means you can cover more ground and
see more scenery before you land, not to land earlier.

Finally, a 500 k downwind is a lot more of an endurance test than a 500
k O&R - that 500 k drive back is really tiring!

Kirk