I think what Vicky is getting at is to start slightly below the right dose so you don't overshoot it. By trying 1u, if you are giving a tiny bit too much, his numbers will improve on that change, if not then you very slowly increase in very small amounts, hold to let settle, and repeat until you get to the best dose.
As to the shed thing, all I can say is that you would think that on smaller doses the shed would empty sooner - if you can completely go with the shed metaphor. I mean, a shed holds a set amount so putting less into it means it would last less time - but how these insulins work is that they bind and unbind repeatedly to (something, can't remember what) and can only be utilized in the unbound state. The binding state allows some of the molecules to be available much later in time (think time-release action, sorta).
Almost all these cats are producing some insulin, just not enough to go solo, so they may need a lot or a little exogenous insulin available. So it is possible for a cat that needs little exogenous insulin to still have some "shed" available even on a small dose.