@Len Look at it this way: A repeat sign means you play it again. Thus one repeat means that the section is played twice. So if it says repeat two times, it will be played one more time than just one repeat thus the total times played is three. And with three repeats you get a total of four times and so on.
But some people might misunderstand that notation and play it only three times if x3 is written above the repeat sign at the end of the section.
The problem is that the performer might not know whether you mean "to be repeated three times" which will mean you play the section four times in total or whether you mean "to be played three times" which of course means you play the section three times in total.
Therefore write "Play 4x" so it is 100% clear what you mean
Whether you write "Play 4x" in the beginning as @Laurence Payne suggested or you write it at the end might not matter that much although I think it makes sense to write it at the beginning. What is really important is that you make sure that it is totally clear to the performer what to do.
EDIT: I have played music several times with repeat signs where the section was played more than twice. As far as I remember it was sometimes not clear what to do, but since the composer was present it could always be solved. When I think back on those events I think I will definitely prefer that it is stated in the beginning how many times it is supposed to be played. Except if it is written the way @suggested by @Meekohi with a box that says 1.,2.,3. and a box that says 4.