What is the Erlang/OTP release schedule? How many major versions are released per year? Is there a schedule you can link to?
Which major versions have long-term support (LTS)?
Since the release of Erlang/OTP 18.0 in June 2015, there has been a major release every year in June, followed by minor releases (x.1, x.2, x.3) in September, December and March. There are also frequent patch packages announced on the erlang-announce mailing list as well as in the Erlang News section of the Erlang Forums.
I'm pretty sure this release schedule was announced on the erlang-questions mailing list, but I can't find it now...
There are, strictly speaking, no LTS versions. The documentation on supported releases says:
In general, bugs are only fixed on the latest release, and new features are introduced in the upcoming release that is under development. However, when we, due to internal reasons, fix bugs on older releases, these will be available and announced as well.
Looking at the messages on erlang-announce, fixes seem to be released frequently for the two previous major versions. Of course, you can't be sure that the bug fixes you want will be available for the release you care about.