I never see a problem with spacing trains… I do use signals, but it’s really easy, no hassle, no micromanagement.
Just by having signals doesn’t mean trains will always stop and go. With proper placement, they only need to wait at a signal once, then they will become spaced out and next time they will arrive spaced out – no need to stop.
The key [in my opinion] is to place a set of signals near the two stations, and a set in the middle of the track. With 2 or 3 trains it will force them to space out once then this space is kept