I would never just keep emailing a provider. Only way would be if she asked me to for certain reasons. After a first appointment, I've had a couple that stay in touch so to speak, but nothing over the top. Some people click better, and I don't mind the occasional hello, etc... I Never initiate that. I obey rules...
As far as chit chat at the beginning of an appointment, I agree that it depends. I Never book 1 hr dates, so I don't mind at little "At Ease" talk. It has never been Excessive. The providers I've seen have been very good at this and knew when both were ready.
I also don't mind a little talk during cool down for a round two, if there will be one. This talk is usually different though. lol...
At the end is normally where some chit chat is more frequent, that I have found. This is the point where I have had some great talks with providers about the Hobby (funny and bad stories they usually lead into), about The Session, future appointments, etc...
I think the Skill of a provider can dictate this. Some are masters of how to calm you and get you going pretty fast. Some also know about a Bad Day and understand, listen, as well being Masterful at getting you going. Some Want to know you a little and will chat a sec before beginning.
I think it varies between People and Providers. While all that I just wrote isn't a "set in stone" guideline. There are times when it's, start engines and go!