This has been discussed many times over the last few years with regards to all tournaments with a completion deadline. The tourneys have a deadline for completion, hence the time check not performed until the round is almost completed Checking time at multiple points during the round would be better but it's not necessary. It's the player's responsibility to meet the time deadline.
Time may have expired on you at any time during the round, even as early as the first hole. According to WGT personnel, the game performs the time check sometime after the green is reached on the final hole. To perform the final time check earlier in the round could complicate things as players save games within the time limit but don't return.
It's probably best just to give yourself a lot of leeway when playing any tourney that allows time for such. Something like don't even start a round in the last hour of a longer time-framed tourney.
A speed tournament means 1) learn to play more quickly, 2) don't bother entering them, or 3) be prepared for unpleasant surprises like you received on the last green.