I don't know about darkening with multiple coats but I just tried it for the first time a few days ago on a bit of joinery in the cabin and it looked quite presentable after just one coat. Also there's none of this fandango in the instructions of "thin first coat with 50% of our special thinners, 2nd coat with 25% etc etc".
I used 5 coats on my teak and holly striped cabin sole, wouldnt say that it got appreciably darker with every coat. I am very impressed with it and it has worn very well over recent months.