A lot of people do not really understand water levels (hose with transparent tubes on ends).
1. This is the most accurate level available at any price. Every time a contractor sneers at my water level and claims his $2000 laser is "more accurate" I don't hire him and put him on my do not call list. He does not not understand enough science to be effective.
2. I have laser level because it is faster for one person, but any time I set forms I double check with a water level. Lasers need calibration, and it is a royal pain to do it with my Bosch. Others may be better.
3. While the most simple drawing of a water level shows one hose with two ends, this is not an inherent limitation. Shorter hose lengths can be joined together with a simple hose outlet "Y" to make three-armed levels, or two "Ys" for a 4-armed level. A plastic "Y" is only a couple of dollars in the garden department of most stores, and being able to check level at many places at the same time speeds up jobs considerably.