I used to run ~37-38 and cutting too many is a bad idea... but it also gives you a high (well, even higher) chance of drawing a bunch in a row late game when you need more stuff. I've actually started cutting a couple in favour of more fast mana rocks, and just trying to mulligan more smartly. You can also consider the cycling lands and the double-faced ones, but these enter tapped which is a big drawback in and of itself (I think they are less bad in monowhite if you have a lot of untapped basics still and recursion, so you can cycle them then still get them into play, but still).