I had a chance to watch the summer migratory pattern of a large school of walleyes I'd stumbled across in mid June. I found a school of active walleyes hanging out on a small weed line. They were there for three days, then they moved to a rocky point 50 yards away. By this time, most of the people fishing the original gravel point had given up. In a two month period they moved 600 yards.
Time of day can plays an important part in solving where the fish are.
Some spots turn on at different times of the day. You can fish over a huge school of inactive walleyes and never get a hit, then come back two hours later and find that they're going nuts. Always double check a good-looking area. If you keep checking these locations eventually you will find active walleyes on one of them. Many anglers think of rocks, sand, drop-offs, and deep water when walleye fishing.