Anecdotally I used discrete math, relational algebra and calculus all during my summer at Microsoft. Proving that a possible architecture was valid in SQL server was very helpful before spending months trying to implement it.
I think many people never use it and that's fine, but I also think it's a nice tool to have in your toolbox if you encounter a problem that could use it.
I think many people never use it and that's fine, but I also think it's a nice tool to have in your toolbox if you encounter a problem that could use it.