Shortcuts...
Cutting coils reduces the total load carrying capacity of the spring. Because each coil has a load capacity (or spring rate), and they all add up to a total spring rate, any time you remove a loop or fraction thereof, you reduce the coil's ability to carry that load. In addition, with progressive rate springs (we've had this discussion before, but I don't recall the result-- are the stock coils progressive or not? I believe they are.), it's not particularly accurate to say that 1 loop = n inches, because the spring rate of each coil is different (progressively so
).
Removing leafs reduces the total load carrying capacity of the spring. By removing leaves from the spring pack, you are effectively lowering the vehicle by "letting it sag."
Is this a "budget rodder" method? Often. Is this safe? Not compared to engineered solutions. Are you going to do it anyway? Probably.
/2 cents
[fixed for typos... now going to sleep!]