Just wanted to say that you're doing great. It may take a month or more to get to the correct dose, but if you go slow with gradual increases, then its a pretty safe process and you don't need to worry so much (I know its all scary at first!) His spreadsheet so far looks pretty normal for a newly diagnosed cat who is getting used to insulin and isn't yet at the right dose. So I'll say it again: You're doing great!
Hypos are sudden and life threatening and can come on with no warning beforehand. So that's the big danger we want to avoid. The other one is DKA, which often happens with very high numbers and/or when kitty is refusing to eat but still getting insulin.
High numbers and complications thereof generally cause problems more gradually and will have clinical signs you can watch for (normal signs of trouble such as lethargy, hiding, failing to eat/drink/groom/use litter box appropriately, limping, struggling to climb.) As long as he looks well and is behaving as if he feels ok, you can keep an eye on him with a few tests a day and monitoring how much he eats. And if you have to miss a test or injection for whatever reason, its not ideal for the goal of regulating him, but he won't be in imminent danger.
Other advice I have for you is to see who in your network could help you by learning to give injections and tests. You may not need them now but its great to have someone trained up who your cat trusts, before you need them. Your vet office may have a tech/nurse/nursing student who is willing to catsit to earn a little extra money and (will know what to do and what symptoms to look out for as well.) Family members and friends can also be taught to give injections and possibly tests as well.
Life will be MUCH easier once he is regulated.
Best of luck to you.