I am in Stu Jackson's camp. If you want your external teak to have a surface like a dining room table, and unless you cover all expose teak after each sail, be prepared to spend hours each season sanding to fresh wood, masking with tape, and then applying several coats of "what ever" finish which only lasts a season or two before the whole process must be repeated.
If quick maintenance, but less than dining room appearance is OK, then the best thing to do with teak is sand off all varnish type coatings. Then just wipe with teak oil every season. Yes, it will look gray and weathered after the first year or so. But it will look the same 10 years later!
I did away with a lot of the exterior teak on my boat. The grab rails were replaced with SS and my cabin top teak "eye brow" is gone.
The teak that remains (companion-way frame and ornamental pads under the primary winches) is now painted with Rustolem's Hammered finished. This paint is metallic looking. Maintains it's near original appearance on teak for a few seasons. Eventually it does begin to wear/crack. But then it's a quick job to sand off the loose spots with very rough sandpaper and put on a new coat over. No need to sand back to bare wood as required if doing varnish type bright-work.
