Usually year long contracts that continue in perpetuity if not renegotiated or terminated. The NCC is essentially there so I don't go starting up the exact same business myself competing with my client. It's not that I can't go work for someone in the same industry, since most of the shit I do, and have done for years, is in casino/poker/sports betting. That would be foolish.
I don't know, I just have a rule that I refuse to sign anything with a NCC in it. Make sure to read those clauses closely though. Back in the day, I know the contract my employment lawyer drafted for me contained a NCC clause which stated my developers could NOT work in the same industry for 2 years after termination of employment. That's a pretty big ask.
NDAs I generally don't care about, because I don't have clients like Google or Coca-Cola. Plus I'm more than eccentric enough to come up with my own ideas -- I don't need to steal other people's. NCCs on the other hand I refuse to sign. Simply because who knows, maybe I'll strike gold sometime in the future, and the last thing I need is some idiot suing me because of a general NCC clause I signed 18 months prior.