These rivers that have been dammed are somewhat difficult to find an area that has consistent wind as they wind through the hills and ridges.
Amen, yesterday's race, we saw 90 degree wind shifts, and +10 knot gusts (from 5kts to 15kts)... One becomes accustomed to watching the puffs/holes work their way down the lake (from the direction of the wind). You start to see the differences in each ripple (I've gotten down to being able to predict the size of the puff within a knot), can predict the lift/header, and begin to understand the effects of land narrowing, and how it can accelerate the winds in the center, and cause rolling wind directions on the edges. If you get good, you can ride the shifts on a lift, and sail 30-60 degrees off the "prevailing wind" and walk past the fleet beating their heads off up the lake. God that's fun! Just as fun is seeing 2 boats on opposite tacks within 100 feet of one another on the same heading!
I'm not going to say you'll ever master it, but eventually you get better at predicting when and where.
I've placed in more than 1 race 1st or 2nd, because I've 1 or 2 tacked upwind when others had to 4-6 tack, by "sailing the sickle" of wind shifts. One other guy in our club, makes me look like a rank amateur at it though... and others are starting to catch on to what I'm doing.
Just sail it like you stole it, you'll be a force to be reckoned with.