You're doing a couple of things with your testing - understanding that will help you be able to figure out when to test next.
First, you're wanting to keep her safe, so when you're testing in the first half of the cycle as the BGs decline, you're checking to see how fast she's dropping so you can catch her and give her carbs if she goes below 68 on the AT.
Second, you're wanting to know how low this dose is taking her so you know how to make dose adjustments.
Cats don't drop at a constant rate per hour, but you can look at the interval between tests and how much the cat's moved, and from that decide when you need to test next. So if a cat is 300 at amps, then 200 at +1, we'd suggest feeeding that cat to slow down the drop (anything over perhaps 50 points/hour can trigger a bounce) and testing again fairly soon to see if the cat is still dropping fast.
In your case, you had +3/91 and +5/86 - that's 5 points in a 2 hr interval. That's Lantus working at its best - holding the blood sugar flat and constant. She's not dropping fast, she's pretty much flat. During the day cycles, she seems to have her lowest point somewhere around +6/+7, so I'd get a test around then, and if it was flat or higher, I'd probably stop testing until pmps.
And just fyi, all of that time spent in normal numbers (roughly 68-160ish on AT) is opportunity for her pancreas to heal. So these are great cycles for her.
