When Can You Just Let Electronic Conversations End?

I wasn’t great with the traditional etiquette of the Emily Post and Miss Manners variety, but I’m hopelessly mystified by the challenge of the proper rules of etiquette for our digital age.

Consider electronic writing — emails and texts — for example.  In the old days, when you wrote a letter to a friend, you expected that someday you would get a letter in response.  Do the same rules apply to email and texts?  With email and texting being virtually instantaneous, is there an expected response time after which you need to apologize and offer a reason for not responding sooner?  In my view, often the speed of a response isn’t as important as getting an answer that is thoughtful — and thoughtfulness usually takes time.  But if I’m infuriating someone because I haven’t responded within two hours, I’d sure like to know that.

When can you just let an electronic conversation end, and when do you have to respond with yet another message?  If I send an email and get a response that is completely satisfactory, is it rude to not respond with a “Thanks!”?  It seems silly to constantly be sending “Thanks!” emails, but I’ll do it if that is the expected etiquette these days.  For that matter, if you go with the “Thanks!” response, must you include the exclamation point?  And is it dismissive or demeaning if you go with “thx” rather than the full, written out “Thanks!”?

I pose such questions because I really want to know if I am inadvertently being a thoughtless jerk in my handling of these nettlesome electronic conversations.  If I’m going to be a thoughtless jerk, I’d rather do so intentionally.