I've been very reluctant to write this post because the issue seems so obvious to me that I must be wrong and will look like a numpty.
Please bear with me while I ramble through my very questionable logic
NDT is extracted from the thyroid tissue of a pig, dessicated and formulated into standardised tablets of 60 or 65 mcg - 1 grain.
In general terms, each grain (tablet) contains both T3 and T4, together with other hormonal elements. The ratio of T3 to T4 is approximately 1:4 (eg 9 mcg T3 : 38 mcg T4). My understanding is that nothing is 'added' - ie the T3 component is an integral part of the extract.
I similarly understand that the some T3 is produced in the human thyroid gland - approximately 15% (ie ratio of about 1:7) - clearly significantly less than that produced in porcine thyroid.
In both cases, the remaining T3 requirement is met by conversion of T4 to T3.
I can see that, for purposes of people who are calculating their dosages for transition purposes, the references to the specific T3 and T4 content are needed. However, thereafter, it's surely just an added confusion.
No-one would take Levo in divided doses, so why is it thought necessary to split doses of NDT to distribute T3 throughout the day?