I think that the ability to have a minimum and maximum response delay would be really cool to have in game. Not essential so maybe something for the future.
For me because I play realistically I hate dispatching multiple units at once because then they travel in sort of convoys and all at once, I know occasionally this would happen in real life but realistically a lot of the time the time for the vehicle to life the station is dependent on how long the staff take to get to it and go.