Might be the chance on project is higher but for me it didnt work. So for me this theory doesnt hold ground.
Why?
I leveled arch on 2 of my alts, havent solved single troll project till i hit skill 450. On my DK i made ~ 60 troll solves and on my shamy ~40. Since it was pre-patch i solved all saved fragments right after skill got 450. Maybe i have some time and can check if all commons are solved and how many repeated. If i do it ill post it here. Havent done any more solves after i burned those trolls i saved for 450 skill so it can be easy tracked since im grinding it on my main which is on ~260 troll solves.