This is something I had to deal with pretty recently. The sequence I needed to model was:

Operator pushes Start

Turn motor on

Motion triggers switch to ON state

Motion triggers switch to OFF state

Turn motor off

Machine changes state to RUNNING

The time between pushing Start and RUNNING is only a couple seconds, but there's a chance that something could jam, the switches could fail, or something I have no knowledge of could go wrong. Question becomes, do I now need an intermediate "In Motion" state for the six or so cases where this happens?

In the end, I decided no, because there was no other transition out of that state than the expected behaviors, so modeling the intermediate state didn't offer me any benefit[1]. Failure to get to OFF state within a certain time puts the system into a global error condition that required manual intervention to fix.

I don't have a real comment here :-) other than to back up your point that modeling isn't as obvious as it first appears to be.

[1] I would have created this intermediate state if this was a complex controller that was likely to have new rules added later. However, knowing it was a simple one-off, I'd just be giving myself extra work for no benefit if I did it now.