Flap settings for Dummies

At the risk of having my ignorance exposed (again), is there any way a
reasonably competant (another problem in my case) can determine
"optimum" flap settings for the most commonly used speeds/
configurations, without resorting to a full-blown Johnson-style test
program?

I have been flying my new (to me) Ventus 2bx for a year now, and am
reasonably comfortable with the following flap settings (speeds in
kt):

40-60 Flaps L, +2, +1 dep on thermal characteristics
60-80 Flaps 0
80-100 Flaps -1
100+ Flaps -2, only happens on badly planned final glides or with
ballast.

However, I'm not sure how efficient these values are for my glider.
Should I stay with 0 all the way to 90kt, or maybe switch to -1
earlier? I mean, I've already give everyone else a big lead just due
to the IQ drop I experience immediately after release, so I'd hate to
think that I'm costing myself even more with poor flap settings!

I have played around some with watching the vario in cruise (TE) mode
to see if it makes much difference between 0 and -1 at say, 70kt, but
it's awful hard for me to tell. Anything else I should be looking
for?

TIA,

Frank (TA)