These have proven helpful in my prep for Verbal for the following reasons:
1) They isolate the most challenging part of verbal for me - moving from question stem through POE to an answer. Because the LSATs seem to have 5 answer choices, there is a lot of practice to be had eliminating answers. Any top scorer (I'm hoping to get there) will tell you that a keen eye for wrong answers can go a long way on the MCAT.
2) They can be used in small chunks of time, yet can help train speed.
3) Logical reasoning is a huge component of the MCAT way of thinking, and it is not a natural strength of mine. This contributes to a better understanding of experiments and hypotheses in biology re: assumptions, support and conclusions. I have felt that an increased familiarity with the structure of arguments is secretly (or not so secretly if you read the AAMC's statements about the test) squarely on their radar.
It wouldn't make sense to decrease the normal verbal prep you'd conduct because of the existence of the LSAT LR section. However, if you need improvement in logical structure / application / eval areas as well as the hypothesis / flexibility in reasoning spheres, I'd recommend flying the LSAT LR up the flagpole and seeing if anyone salutes.