I'm going to say this from the other side of the boat as one of those clients who has been deeply attached. If a T is going away on holiday then they should provide a back up plan for when they're not going to available and this should be discussed before hand in session to something that is reasonable for both. My T didn't previously allow contact during holidays but let me have that plus a full session in august.

Up until recently I used to email my T once a week- but I also feel like I over did it when I went back to London for 17 days and emailed multiple times during the week. Where I am now I don't feel like I need contact now and haven't emailed since the 18th, which is a big thing for me.