People taking synthetic T3 often have an afternoon crash with once-daily dosing only because synthetic T3 has a short half-life.
Due to the thyroglobulin in it, Armour's effects seem to last longer and many people are able to take it once daily with no problem (no afternoon crash). However, I am aware of people that divide the dose.
The only problem I see with that is the fact that the second dose would need to be taken at least one hour before/two hours after last food/drink other than water....and 4 hours away from any iron/calcium. Reason being: Armour also contains T4 that has absorption issues.
We each need to figure out what works best for us.
Thanks for providing the ranges. Your levels with Armour in your system are still lower than what most people would find comfortable so, without a doubt, a dose increase is in order.
Best of luck to you moving forward!