A budget, not a threshold
Degradation is cumulative. A dry peptide that spends two days in transit at ambient temperature has used a small, calculable part of its stability budget. The same material left at ambient temperature for six months has used most of it.
Understanding it as a budget explains why transit is acceptable while poor storage on arrival is not.
Where the risk really is
The largest risks are usually after delivery: a parcel left unopened in a warm room, material stored at the wrong temperature because nobody read the label, or reconstituted solution kept far longer than intended.
Transit is comparatively short and is packed for. Storage is long and is often unmanaged.
Packaging
Insulated packaging slows the rate at which the contents approach ambient temperature. For lyophilized material the aim is to limit peak exposure over the expected transit window rather than to hold a precise temperature throughout.
Research use only. This page is explanatory and does not recommend any use, quantity or procedure. REVIVE LAB supplies reference materials for laboratory research. These are not medicines and are not for human or veterinary consumption. Anyone considering the use of any compound in humans should do so only under qualified medical supervision.