I agree that the time limit is too short.

This is my solution:

-against NPCs: 1-2 minutes (time limit might be a security net related to how many players can be in a TT game at the same time with same NPC due to this being an online game, so this way no one can just sit there with a TT window running)
-against PCs: challenger choose a time limit, up to a certain limit like 5 minutes
-against PCs in tournament: time limit depending on tournament time limit rules, most TCGs and CCGs do not have a time limit for turns, BUT if opponent or a judge thinks player is taking exceptionally long they can be put on a time limit for said turn and penalized if they fail to finish in time, but since TT tournaments don't have judges, there would need to be a time