Yeah, most often with Soma or alcohol (but not even all that often with alcohol any more.)
I find it pretty easy to work out my limits for a good dose with most other stuff. Although I haven't always stuck to them by any means. Usually re-dosing too quickly has been the issue.
But Soma is an especially tricky fucker for working out the optimimum dose. The worst that usually happens, provided you don't go too mad, is that you just very abruptly conk out. And just have to hope you weren't eating or drinking anything at the time as it is so abrupt that things get messy.
Apparently the Indian Pain O Soma pills that the clearnet market is flooded with are unreliably dosed, which would explain a hell of a lot! More expensive big pharma brands are said to offer a much more consistent and predictable experience.
It goes without saying that things can get a lot more serious than food or drink spills on the carpet or sofa if you're talking about taking too much heroin.