It's risky. Benzodiazepines exert effects on our bodies long after we believe they've worn off. Gather 'round children, it's time for Uncle Kief'(')s story time.
A few years back my posse of 4-5 users were hanging around waiting. We were all sick, so one guy took 1mg Clonazepam to help with symptoms. It was all he had. We'd been up all night sick, so you can imagine how we felt. This must have been around 5:00 - 6:00 in the morning. Well, we weren't able to score until around 9:00 that night. I remember it very clearly. We were all a typical group of junkie/friends, helping each other, using similar dosages, similar tolerances etc.
Well, we scored and we went back to the spot to do our shit. Well, the kid who had taken the Clonazepam over 15 hours earlier instantly turned blue and stopped breathing, while we were all simply "well". We had to call a bus to collect him and we took turns breathing for him while we waited.
Case in point: 1mg Clonazepam, 15 hours earlier, a normal dose of Heroin, what would've been certain death for my friend.