I think you would have been ok with the increase. The .5u dose didn't do anything other than hold the numbers flat. That's not a bad thing, but shows the dose had no effect in lowering the numbers in the middle of a cycle.
If you can get a test around the middle of a cycle, you can get an idea how effective it was.
I'm not a big believer in the "settling in" theory with non-depot insulins like PZI/Prozinc. I think the effectiveness of a dose is revealed fairly quickly, within a cycle or two. I adjusted Bob's dose more or less on a shot by shot basis, and if he ever goes back on the juice, I'd do things the same way. But that's me, treating my cat. And most people probably don't agree with that method, and that's fine. And the primary reason I no longer advise much on dosage. 'My way" is aggressive and probably less safe, or at least more stressful. And safety should be our top priority when giving advice to other people's cats.
You have to do things your way, with your cat.