Wheel Size

In regards to practice and learning all these skills: 180’s, idling, riding
backwards, etc., what size uni would be the best to use? I ride fairly
competently mounting, going forward, and turning on all the sizes, but need some
work on the skills. Sometimes the 24" seams ideal, while at other times a 20"
feels right. I’ll have to admit that most of the time the temptation is to just
grab the 26" and go cruising, but that’s not helping my skill level too much–.
Any and all advice in this area will be much appreciated. I recently purchased a
Pashley Muni and would like to say what a nice ride it is. The only mod I had to
make was to install a Viscount seat. What a great Uni! Thanks again, Mike