Personally, if I wasn’t cashing $500,000 checks on a regular basis I’m certain the tellers would be suspicious of even something as measly as a $350,000 check.
For me, issue is that my real name is so long that it doesn’t fit on one line for checks. Instead of writing “Christopher Augustus Schrödinger Heisenberg” (and people are always uncertain on the spelling, among other things), I just tell the to make my checks out to “CASH”.