Fair enough a 5mph wind hitting the pellet at 10y will move a pellet at 45y more than a 5mph wind hitting it at 30y & it's a good effect to keep in mind but it's just one small factor in trying to judge the wind.
I've shot quite a few grounds in FT & HFT & your rule of thumb doesn't hold out for a lot of them, if you factor in terrain, trees & any other obstacles the pellet can go anywhere
it can move more or less that the wind at your face or even move the opposite direction.
You can use the wind at your face as a guide but it truely only lets you know what the wind is doing at your face, you need to use other factors such as:
Grass, Tree, leaf movement
Wind trends as you are waiting to shoot
Face plate hits & misses
Listen to what other people are saying (take with a pinch of salt)
Even seeing whether a new starter hit a target can help.
The main thing in getting better at judging wind is you need to practice shooting in wind, just remember it's never to windy to practice. As you gain more & more experience shooting in wind it will become easier & easier to judge but it will still stick it to you now & again