I see your point. I will say that the reason I use this tactic is that it allows me to run at a decent time compression, while not worrying about missing potential targets due to the sometimes random nature of the crew's contact report. In the end, I believe that it saves me time, as I can safely run at higher TC without these worries.
I will say that I have yet to be fooled by this tactic. The studdering caused by vessel spawning is quite distinct, and I have even learned to gauge the size of a convoy based on these patterns. This is what I meant about the "feel" aspect of my justification
But I will repeat that when the studder feels like a contact, it ALWAYS is a contact. I can't remember being fooled by some other element that could potentially cause a studder.
The best way to describe this studder is a quick freeze, followed by immediate and intermittent studders for a couple of seconds.