I thought the same thing for the past wo seasons. I would bring a box full of streamers and work the whole lake; sinking, floating, or what ever other method I could come up with. I haven't got as much as a snag using flies until this year. I stoppped and paid attention to what the fish were doing. The lake that I fish for stockers receives a lot of pressure particuarly on opening day. All the doughball guys take their share. This year I had the same results the first day but for awhile I just sat there watching what was going on. I noticed a lot of finning fish on the surface. That night I broke out the trusty literature and read that finning fish are usually feeding on nymphs just under the surface and not on dry flies or streamers. I tied up a bunch of wet flies and fished them the next day and outfished everyone else around. I had to go chasing fish finning fish but it paid off.
The most important thing as buddy said is to pay attention to what is going on and you will be rewarded.