I have mastered mixes from Bruce Swedien (which didn't require much at all) but the vast majority...like 90% come from non-commercial clients who are not mix engineers.
I honestly can't say the 90% normally require more tools
than the 10%. Maybe I'm lucky.
What seems to be fashionable is so called mastered mixes somewhat ruined by a limiter, usually subtle distortion, and loss of punch, with hopes of magical expansion to make everything cleaned up at the end of the day. And almost every project, when I ask...the client relied on a limiter to obtain the majority gain. This is why it's sad to read all these posts about the "best mastering limiter" when in fact your "best mastering limiter" should only exist for a few extra dB's.