Oh the threads back.
The 3 minute flow was always very tricky for tower to achieve.On single runway it's impossible because the gaps just don't fall that way.On duel runway it can be done,but only with a certain combination.Also you couldn't fire off outbounds 1min apart,as it always crept to 2 mins,so 3mins became 4 etc.Then some days it's 5 mins which is 30+ miles on radar.No one asked the Tower about 3 mins.I could give you 3 mins,but that a gap down the drain.
Also CDC might have transferred previous traffic to GMC north or south,and has to leap between the two to work out a delay for you.If it were a local they may not have the English skill to explain in non standard R/T.If you'd asked me ''Any delays''when I was there,I would have said ''Yes,give me 20 mins to work it out''.
So why bother with 3mins if it's tricky to achieve.It just delays more outbounds who have no flow requirements.It puts an enormous r/t load on CDC,trying to explain a useless system to bewildered pilots.