Pretty sure you'll need higher than normal pressure, but not sure of the exact amount.
Funny story. Early last week I got a call from a local TV news station that wanted to interview me on one of our sites to explain the sprinkler blow outs, and the big rush as to why everyone calls at once in the fall. I declined it due to too much work, and not enough time. I wouldn't be able to handle the excessive phone calls that might come with having a spot on TV. Later that night TomTom let me know that the station had a spot on their nightly news with a different contractor that I know. It all seemed fine, until I see who I guess is one of his employees, drag up a small construction style compressor that gets plugged in. I almost fell off the couch.
Here's the thing - for the most part, it can be done with a small compressor. Not Mike's mega systems, but on cookie cutter type lots, it will work. BUT!!!! They take so long to do, one zone at a time, and cycling the compressor to let it build pressure back up, that you can't get enough done in a day. So you would lose out on potential customers because you would get further and further behind. With the larger compressors, even with my 100 cfm machine, I can do 2-4 zones at a time designed at about 10-15 GPM. I can't see using those itty bitty compressors on systems over 10 zones.