We used Semco for many years, after giving up on teak oil. Since then we have migrated to Cetol and finally to proper varnish
. However, we did not have teak decks.
If I were to deal with teak decks, I would try Semco, which—as an earlier poster stated—is easy to prepare for a recoat. Anything else mentioned is much more work. Whatever you use, there will be maintenance
. Semco is no exception, but is by far the easiest to maintain in our experience. It isn’t varnish
by a long shot, but it will protect the teak.