To begin all NHL games both teams are awarded one timeout. They can use it at any time during the game except after an icing. Most coaches use it to set up a play late in a game or to give the top power-play unit a rest if they’ve been on the ice for a while and the coach wants to keep them out there.
However, there’s one other use for the timeout and it’s a big one. In the event a team wants to challenge a play for goalie interference, they must risk their timeout. If you don’t have your timeout, you can’t request a challenge.
Thus, holding on to that one timeout can be crucial, especially in a game in which a team is leading.
That’s why I don’t use it a lot. I want to really save it because if goals are scored on an interference you really want to save it. If I think we need it because our defensemen on the ice are exhausted and Gilly (defense coach Ryan McGill) wants to keep them out there then I’ll use it but it’s tough because you’d hate to see a tying goal go in when there’s a goalie interference that you might be able to challenge (and you don’t have the timeout). -Gerard Gallant
The purpose of the timeout in hockey has essentially changed.