When I ordered our cut to size worktop I got them to cut the back at a 32 degree angle so it was easier to trim to fit the less than straight/level wall it butted up to.
clever! although i guess the strength might depend on the grain direction if using timber?
in our case the worktops were along newly plastered walls so they were fairly straight.
When I ordered our cut to size worktop I got them to cut the back at a 32 degree angle so it was easier to trim to fit the less than straight/level wall it butted up to.