RE: the can
here's what I'm using
Primos "The GREAT BIG Can" long range estrus bleats for all phases of the rut
I do not hunt in a tree stand because I feel like I want the deer to hear the call coming from their level, not up in a tree.
I usually make ONE SINGLE bleat after I get on stand and everything is quiet. If there is no wind it seems to work best. If I haven't heard anything for about a hour then I'll do it again. Sometimes it works like a charm, it just seems to matter if there is a buck in hearing distance.
Hope this helps a little