turboprop

Watching steveokinevo on YouTube, I can’t help but notice that he would always operate 100% on hi idle when he flew the TBM 850. Now I’m no TBM pilot nor do I fly any turboprop, but I was always under the impression you were in LO idle on the ground, and would switch to hi idle before takeoff...

I'm looking to get myself up to speed on turboprop systems and op's, right now the Garretts in particular. Anybody know of some good reading material on the TPE331 & PW PT6? So far, I have not been able to locate much on the internet. Thanks for your time,