dado depth sizing

[Don Jeansonne]

I want to make some shelving units in plywood and dado the shelves into the uprights. My question is for 3/4 inch plywood, what is the recommended depth especially when doing two shevles into an upright for two side-by-side units ( one upright with a dado on each side). Would a 1/4" depth on both side leaving 1/4" of remaining material weeken the upright too much?
Any guidance ?

[glenn bradley]

I tend to go 3/8" on the single sides and have gone 1/4" - 1/4" on center dividers for permanent, glued-in shelves. For peace of mind I tack the back along these "lines" as well as the usual 'around the outside/down the middle' pathways.