To me, the holding doses several days stuff is more to take some of the stress out of it. For one thing, you don't need to get spot tests every cycle if you are taking that approach, you can start a new dose, let it go for a few days, get a nadir test in here and there, maybe run a curve or get more spot tests on a weekend, and then make your dosing decisions then. A LOT less stressful than changing doses every day or two and needing to get in plenty of spot tests to be sure you aren't shooting too much insulin.
With PZI, I don't think it takes all that much time for the insulin to build up, there's no extended shed as far as I know, although I do think there is a small one. As for their body adjusting, from what I have seen that tends to work in the opposite direction of what you want. If their body adjusts, it will resist the insulin. That's where you get stuck in higher #s and need a BAM dose to bring them down (sorry this one didn't work - I had high hopes!!!).
Of course, other people see it differently, so I can't say that my perspective is right, that's just the conclusions I have come to based on what others have taught me here, what my own experience has been, and what I have observed from the limited range of cases that I have followed here.
It appears to me that Blackie is stuck in higher #s, so she may need more insulin to get a breakthrough. I was hoping you would get dramatic improvement on cycle 1 of 2u, and then might be able to back off the dose a bit. No go though, so I would probably keep this dose long enough to let the overlap build up - 4 cycles I would say - and then if you are still not seeing any improvement I would raise it.
I generally don't argue against holding a dose a few days longer if there are signs of progress, or if there are practical concerns, like someone wants to do curves on the weekends and then make decisions at that point. Or if there isn't much data and you wouldn't want to raise before gathering more data to see how a dose is doing. But you are getting in lots of spot tests that so far are showing (to my eyes) that the doses are too low, so in that case, assuming you are home to monitor the effects of dose changes, makes sense to me to raise it every 2-3 days, rather than waiting longer.
The key thing when you are raising faster like that is to keep an eye that the PSs aren't improving REALLY dramatically, and if you do get a lower PS, or I would say once you get to shot 3 at this dose regardless of the PS, I would get in an early cycle spot check, maybe +3 give or take, to make sure it isn't too much insulin. If it is you feed some LC, or HC if warranted, to balance it out.
If she is acting well though and there are no signs of ketones, you can wait 5 days if you want to. But I don't think the likelihood is high that you will see better #s if you aren't seeing them in the 1st couple days, that's what I'm trying to say, longwinded-ly. :lol:
You can wait 5 days, but know that you are doing that because it's what you want to do (and you may have good reasons, I'm not saying there's anything wrong with doing that). That is, it's not because there is much hope that on day 5 the results will be any better than they were on day 2. If the PSs are gradually coming down, then yes, you would want to hold a dose to see if that progress continues. But if her results are like they have been lately, just not much movement in the #s, then I don't think there is a need to hold the dose longer out of some idea that her body will adjust and the results will improve.
To a large extent, I think the thinking that a dose should be held for several days comes from when one isn't home-testing. Back when I didn't home-test and I went to my vet for curves, it made sense to hold the dose for a week or longer b/c we had NO idea what was going on - if the PSs were improving, you would want to hold the dose, so waiting some time like that made sure that things got shaken out some before the vet saw the #s. But once you are hometesting, you can see what each shot is doing. If the #s aren't coming down, then you can conclude right away you need more insulin. If the #s are coming down, then you can conclude this dose is helping, so you may want to hold it longer to see where it goes.