25% tt near enough, that's a lot of 'on your own' racing. For the people who have been here awhile, that's normal. But, if new players join to find themselves racing on their own, like billy, it would be a bit of a turn off.
TT races only in /tt sounds good, also would keep the TT records safe (main race tt records would be harder to get that /tt races, that you can easily start again with /tt).
So yeah, I'm all for the idea. Maybe replacing some tt races with duel/normal might spice it up, but that's quiet a lot of work with resetting a new grid location for the other players.