I feel this is a great exercise for all climbers, but I feel the biggest gain is when the difficulty hits V4.
Pick a series of 5 problems just under your maximum (about 85-90%).
Climb each problem such that you will always touch each hold with both hands or match hands on every handhold. Climb each problem 2-3 times doing this with minimal rest in between attempts, and resting longer periods between the different problems. Make sure to pick different angles of wall, and different styles of climbs.
One thing I like about this is it forces the climber to figure out ways to create lower body tension to match the holds. Sometimes, it forces you to stop on smaller holds when you would normally crank to the next. This can become a very difficult exercise on compression problems.
The main reason this is more effective on harder climbs is that with easier climbs, holds are configured closer together and more down-pulling in nature. As climbs get harder, hold position varies much more and the spacing between holds may be further apart.