I do not use oven bags at all. That's an unnecessary weight to bear.
First of all, I don't know what you guys use for a backpack. Currently, my most typical backpack is a Golite Breeze. Whenever I purchase a new backpack, I spray a little waterproofing spray over it, either inside or outside. The result is something that is virtually waterproof. So, I never worry about stuff inside getting wet while I am on the trail. Now, I do use some stuff sacks inside the pack, mostly for things that don't tolerate any moisture, like my down sleeping bag. However, a cuben fiber stuff sack there weighs less than anything else, and it seems to complete the water protection job even after I arrive in camp and I am unloading everything during a rain storm. I will always have a completely waterproof rain parka shell in there, and it can always be used to protect fragile items from wetness if I don't already have it on. Some of my gear came with its own built-in stuff sack that is not waterproof. If I get extreme, I might use some flimsy produce bags to back that up, but only if I expect some wet and deep stream crossings.
The most water-susceptible thing that I carry is my camera, and it is in its own weatherproof case with a produce bag inside, just for a wet stream crossing.
On one 5-day trip a year ago, I got rained on each day. I figure the maximum rainwater that got in was about one drop.
So, no, I don't need no steekin' oven bag.