We use these for trenching in dripline in difficult conditions, and for other trenching work. The wood handles last a long time, unless you are careless with them. Lee Valley sells spare handles and I keep a couple on hand. I have not replaced any for several years now. They work best if sharp, of course. Sharpen them with a large chainsaw (round) file on the inner curve of the tool and clean up the outer edge a bit with a flat file if
Trenching depth: typically about 6″ to 8″, any deeper than 12″ and it is a bit awkward.
I also find them handy for general excavation (e.g. digging out a bit of extra soil for
a valve box) and one of the people who works for me uses one in his garden a fair bit.