Problem with using it in light aircraft is that you need an accurate enough fuel gauge - which basically means a sight tube. You'll get that in many microlights, and some vintage aeroplanes - but few spamcans.
Given that, in most light aeroplanes, where it's reasonable to do fuel planning on the basis of predicted performance (plus a bit of a safety margin of-course), I think that the method will work, but using time rather than fuel state.
G