i have repeatedly taken "insufficient material" draws, when the other player had pieces for a checkmate. it seems that atleast half the times i should have won on time, i end up with .5 for insufficient material. i may not be great at this game, but i know what is sufficient for a checkmate. after it happened a few times (and i talked myself into thinking i just saw something wrong), i sent an e-mail to chess.com, but never heard anything back.
There are stipulations in place in both UCSF and FIDE rules that a player can claim a draw if their opponent is purely trying to get a win on time. These rules require arbitration by an official, and so it is difficult to incorporate them into an online site such as this one. Chess.com has tried to do so by expanding the definition of "insufficient material" to include some situations where a mate is theoretically possible but not forceable, such as KNN vs. K.
Can you point us to at least one of these games where you were awarded a draw for insufficient material when you think you should have won? All your games are archived and available forever.