How long is a "hand of turnings"

During the parts of books from a treecat POV they often refer to number in terms of "hands", and time in terms of "turnings".

I think treecats have 4 fingers, so would a "hand" of scouts be 4 scouts?

Is a turning a Sphinxian year? I think that is 5 years?

So would that make a hand of turning about 4x5 = 20 years?

In one book someone mentions that the bright water clan has had the same nest for "over 10 hands of hands of turning". Would that be 10 x 4 x 4 x 5 = 800 years?