If one of these custom playlists encounters a wendy filtered track what happens (player plays 3 different songs from that year, player plays 2 songs then moves on, player crashes)

Player selects three non-wendy-filtered songs -- unless there are fewer than three such songs, in which case player has to select all of them.

Nice to know why also.

I'd say it was probably due to our high personal standards of professionalism and earnest desire for good quality software

Peter