The MLL 3hr rule does not apply when waiting between flights. No problem with in/out -- I just check with the attendant when leaving, telling them I'll be back; dunno if that is even needed though.

Not sure about Signature Suite access longer than 3hrs. I don't see any special language saying it's any different than for MLL with connections.

Edit: Found a copy of the original press release here, indicating that a long layover should not be an issue for any of the lounges, including Signature Suite. It would be nice to find a direct link to the AC website though. https://blog.rewardscanada.ca/air-ca...o-three-hours/