Ships paths using RSRD

[Armistead]

Overall, the entire game, just want to know how this works.
Take the Midway TF to be simple. It travels from Japan to Midway.
Can you pick it up anywhere on it's course or will it spawn just in a few places?

Often I will damage some capital ships and track them. If I track them long enough eventually they will vanish, even if on radar.

I've about finished a career and found the Yamato in the Bungo April of 45
on it's final one way trip. Got three in the Y, then shadowed it. I still had it on radar and it just vanished. It was near a port, but not close enough to do a port vanish. I stayed on patrol same area for several days used all my torps, when ..wala, the same Y TF shows up where I lost it. Maybe it pulled in port for fuel....lol. I tracked it for a day and it vanished again on radar. Is there a time limit before this happens?

Back to the start, just want to know if you can historically be at the right place on course, at the right time, will a TF show. I ran into the large Java force of 50 ships near Jolo, so it seems you can attack these historical convoys anywhere on their course to battle.