Not enough can be said for time on the water, but don't just go out to catch fish, go out to enjoy the time on the water.
Now that being said here is something to try next time you are out. Instead of pulling into a cove with a ton of standing timber try to find one with a balance of chunk and timber with axcess to deeper water this way it will give you a variety of cover to hit without running all over the lake, Then once you find out what structure the fish are relating to you can concentrate on those with different techniques untill you find the one that is working best.
That should eliminate alot of water so you don't kill time fishing where they ain't.
P.S. A map helps a ton.