Lots I could respond to, but I’ll mention a couple.
Typos: Goldie-Lox should be Goldilocks unless you are making some point that escapes me.
And marco is obviously intended to be macro.
You mention the assumption that HbA1c is limited by the lifetime of RBCs, though you properly don’t give it much weight. In fact, the 90-day idea is based on the assumption that conversion from HbA to HbA1c is irreversible. But all chemical reactions are reversible, the only question being how fast the forward and reverse reactions occur. AFAIK, the only measurements for HbA<->HbA1c were those done by Henrik Mortensen in the 1980s. The following is from the misc.health.diabetes FAQ, written in the mid or late 1990s, after Charlie Coughran discovered the Mortensen paper. I would change some statements now, especially due to the rise of CGM, but here it is in the original.
In the early 1980s, Henrik Mortensen and colleagues at Glostrup University Hospital, in Denmark, measured the reaction rates in vitro. Their results showed the assumption of irreversibility to be untrue. In fact the reverse reaction (HbA1c to HbA and glucose) proceeds at about 1/8 the rate of the forward reaction, which is very far from irreversible. Mortensen et alia also built a biokinetic model based on the measurements, and validated the model by comparing its predictions to actual patients. See references below.
Among other things, Mortensen’s work shows that after a change in average bG level, the HbA1c level restabilizes after about 4 weeks. This has several consequences. Clinically, the most important are these:
First, the HbA1c is an exponentially weighted average of blood glucose levels from the preceding 4 weeks, with the most recent 2 weeks being by far the most important.
Second, measuring HbA1c less often than monthly results in unmonitored gaps between measurements. To use HbA1c as a continuous monitoring tool, you need to check it at least once a month.
Third, it is worthwhile checking the HbA1c of newly diagnosed patients as often as once a week to determine the effectiveness of the newly imposed treatment.
Reference: Mortensen HB, Christophersen C: Glucosylation of human haemoglobin a in red blood cells studied in vitro. Kinetics of the formation and dissociation of haemoglobin A1c. Clinica Chimica Acta 134:317-326, 15 November 1983.
Reference: Mortensen HB, Volund A, Christophersen C: Glucosylation of human haemoglobin A. Dynamic variation in HbA1c described by a biokinetic model. Clinica Chimica Acta 136:75-81, 16 January 1984.
Reference: Mortensen HB, Volund A: Application of a biokinetic model for prediction and assessment of glycated haemoglobins in diabetic patients. Scandinavian Journal of Clinical and Laboratory Investigation 48:595-602, October 1988.