Completing a dose with a second syringe, and the dead-volume arithmetic

Posting this under the heading it deserves: Completing a dose with a second syringe, and the dead-volume arithmetic Everything below is what sits behind that.

I have read the maintained page on this and I still have a gap, so I am asking rather than guessing.

Context: tirzepatide, 19 weeks in, currently at a dose I reached by the standard four-week steps. Everything below is my own record rather than anything a clinician told me.

The specific question is the one in the title. What I have already checked: the labelling summary on the relevant documentation page, the two most-linked topics in this subcategory, and my own notes from the last 10 weeks. What I could not find is whether the answer changes at higher doses or whether it is the same arithmetic throughout.

If the answer is "it depends", I would rather know what it depends on than be given a number.

If you have to inject at a different time of day than usual, that is a much smaller perturbation than it feels for a weekly compound with a week-long half-life.

Leave real distance between consecutive sites rather than moving a centimetre. Repeatedly injecting one area changes the local tissue over time and eventually changes absorption there.

The reasoning is more useful than the number, which is why I have shown it.

Leak-back after withdrawal: a small amount of liquid on the skin after withdrawal is ordinary. Whether you lost a "meaningful" dose depends on concentration and your target dose, but some leak-back is universal and does not need to be treated as an error.

Air bubbles in a subcutaneous injection: the honest risk assessment is low. Tiny air bubbles in subcutaneous tissue do not behave like an air embolism in a blood vessel. A few air bubbles are not a reason to restart the entire injection.

I would rather say I do not know than round it up to an answer.

Noted, and I have changed what I was going to do on the strength of it.

Taking post #53 at face value and following it one step further.

A genuinely late dose: the labelling generally says that if the next dose is more than a couple of days away, take it as soon as you notice. If the next dose is close, skip it and resume the schedule. The reasoning follows from the long half-life; you are perturbing a slowly moving average.

The strongest argument against my own position on completing a dose, stated as well as I can state it, since nobody else has yet.

Picking up post #71: that is the part I would want checked first.

If you have to inject at a different time of day than usual, that is a much smaller perturbation than it feels for a weekly compound with a week-long half-life.

This is the sort of thing that ought to be settled and apparently is not.