Another TAv (for preference) user here … especially on the more recent bodies where the high ISO capabilities are so very good
The only time I'll select P is if I'm in a hurry to get a flash exposure with the on-camera flash … it just seems to work better.
For me, Av and Tv are (mostly) covered by TAv, but I do have occasion to use Tv with auto-ISO set … to make sure I get the best possible exposure in potentially low light whilst maintaining a specific shutter speed to freeze the subject.
The modern Pentax DSLRs are wondrously complex devices that do try to provide virtually every combination of features to cover most scenarios … and allow you to save that configuration in a User Mode, for next time
It'll be a very wide-ranging photographer that regularly uses more than 50% of the modern camera's capabilities, but that combination may well be almost unique to him
Just occasionally I find it both refreshing and relaxing to step back from all the latest wizardry, fit a manual lens to my *istDS and "get back to basics" for a few hours