In reply to Matrix:
Lee Sheftel started climbing at 33 and climbed 8b+ at 59. Your age is virtually irrelevant at the grades you are climbing and aspiring to.
http://stephdavis.co/blog/climbing-and-age-limits/
Would you expect to play grade 8 on the piano if you started in your 30s and practiced once a week? Would you expect to run faster if you ran once a week? Would you become a better ballet dancer if you practiced once a week? Climbing once a week, even a focused and effective session, is going to severely limit your potential to improve and there is no dressing this up.
Rock climbing involves a combination of movement skill, head skills, and physical factors (strength-to-weight, forearm endurance, flexibility). That's the order of importance for most people. Movement, often the most important factor, can only be practiced on a wall, board or outside.
You are top-roping 6c and leading 6a+. You have a marked weakness in 'head skills': leading confidence, fear of falling perhaps, or leading tactics. These can be addressed effectively on a lead wall or outside, working with an experienced climber. This is how most coaching holidays achieve their improvements.
Supplementary exercises like finger boarding, pull-ups, or yoga/stretching help physical factors and might help your climbing if they directly address a significant weak-point. Finger strength-to-weight is your most likely physical limitation so finger strength training and weight optimisation are most likely to benefit you. As a rough guide, doing more than 25% of your climbing training on supplementary exercises is probably wasting your time. stp has climbed for ~35 years, has great movement skills and head skills, so doesn't need to practice them as much as you do. Supplementary training is really helpful for him. It is less helpful for people like you who usually most need to practice moving.
If you're happy leading 6b/+ then practicing in a focused fashion once a week with a little supplementary training will achieve this. Coaching your leading might reduce the gap between leading and top-roping grade. If you want to get significantly better you need to build more climbing around your life or modify your life a little to allow more climbing.
Post edited at 10:37