To correct you further 17 years working in a bookies, 10 years of not giving a shit anymore, throwing out underage kids, being threatened by Albanians and having an argument I can't win with punters that have been been betting 5 minutes demanding that there is nothing wrong with Man U winning...
You wouldn't need a tic tac for 20/21, not that you need one now anyway, it would only be used as an SP returned in the unlikely event of a similar number of layers offering either Evens or 10/11 at the off. It would never be chalked up on course. The same principle as 85/40 and the once seen...