Actually, the Link Trains that run between terminals have a maximum waiting time of 4-8 minutes depending on time of day and they run 24/7:

https://www.torontopearson.com/en/tr...nal-link-train

As mentioned, the station is at the entrance of the hotel, one level up from the lobby level.. It is a very short ride to Terminal 1 from Terminal3/Sheraton.

Living in Toronto, whenever I have a really early flight I always stay at this property to avoid hassles of getting to the airport in time and I almost always fly out of Terminal 1. Trust me, depending on an off-site shuttle is no advantage. You can quite validly book other hotels based on price, amenities, etc., but for convenience this one wins hands down.