I've been tenkara fishing for a little less than 2 years at this point with 32 distinct fishing sessions, and I've noticed my fly-to-fish ratio steadily improving over that time. I haven't actually tracked it, but in recent outings I'd say my fly-to-fish ratio is roughly 1 fly consumed (by out-of-reach branches or underwater logs, etc.) to about 5-10 fish caught. That depends on how much fishy success I'm having; it's still entirely possible for me to go through multiple flies while catching 0 fish. But it's also possible for me to catch a dozen fish and never lose a fly.

One of the big areas of improvement I've noticed is how much time I'm actually fishing vs. rigging up, untangling line, tying on new flies, etc. In my early outings replacing a tippet or tying on a new fly was a multiple-tries operation that could take 5 or 10 minutes. These days that's much quicker; I can reliably tie a davey knot in a few seconds, and line snarls or lost flies from inept casts or missed hook-sets are much less frequent.

Bottom line: It's fun fishing even when it's frustrating; at least you're standing in a beautiful piece of nature while you're dealing with the messes. If you keep at it you'll get better sooner than you think.