How are repetitions played more than twice written on music?

I am familiar with the repeat sign, which indicates repetition only twice, but I noticed in a lot of Steve Reich compositions that there were melody repetitions that could last up to 20 full minutes. Which got me asking: Is there a special notation for repeating sections more than twice? Or do these repetitive compositions simply utilize pages upon pages of the same 2-4 bars?

The way I've usually seen it in scores and parts is a repeat sign with 3X above it for 3 repetitions, 4X for 4 repetitions, etc.  I'm not familiar with Reich's scores so I can't tell you how he does it, but it wouldn't surprise me at all if it were all written out.  

You still use repeat signs, but either add text above the affected passage that says, "4X," or "repeat until directed," or something like that, or you can use a first ending bracket at the repeat sign, but instead of being marked, "1." to indicate 1st ending, it will be marked, "1., 2., 3., 4.," to indicate 4 repeats before moving on to the next section.  You can also indicate different treatments for each of the repeats in text above the affected passage.  For example:  1. p, 2. ff, 3. mf.... 

Hope that makes sense without pictures.