Today was really quite busy, most coasters going between 60-100 minutes and Samurai, Rush and Vortex being around 45-60. Really have no clue when schools break up/half-term dates but, being an off-peak day I was a bit surprised. I think if you like the fastrack then go for it because it seems people are eager to go now lockdown's easing off and its almost certain that the next few weeks are going to be REALLY busy.
I personally also dont love fastrack and you should really be able to squeeze all the coasters in and its quite expensive but, again, its up to you!