Pyramid plunder gets annoying after a month lol. I do think it's best way to get to 91 though without boosts etc. That said though, I was informed by a few friends that you can actually do Prifddinas thieving at 87/88 if you have the Abyssal Lurker and its scrolls (It boosts 4 levels).
I feel that I have better things to do rather than doing any actual training for Thieving until I hit 91 because it gets annoying with always having to boost again (I made overloads at 94/95 Herblore and hated it).
the game "the sims" was originally going to be an architecture based game. the player would design a house then the sims would judge it. some time in development, more interest was directed towards the sims themselves and the game became a life simulator instead