At Flamenco Tours Tarifa this Summer the percussionist Ruven Ruppik gave a talk about studying Tabla. Apparently the traditional way is to study bols for one year. The one he showed was called Rupak Tala and was interesting as it is in a group of 7 beats which are subdivided into 3 groups as follows.
Tin Tin Na | Dhin Na | Dhin Na
This vocal phrasing is then sung with the hands doing a particular counting. Once the tempo is established with the hands and voice. The bol can be doubled, halved, done as triplets and then off the beat creating a dizzying amount of permatations.
Here is a video of me practicing.