Why total testosterone and SHBG rise together, how to work out whether your free testosterone is genuinely high, low, or normal, and which measurements are worth paying for.
You can draw blood on any cycle day. The question is which analytes move with cycle phase, how much, and how to record the phase so your own longitudinal data stays interpretable.
A technical read of the MPMD/Marek Health blood panel: which assays are chosen well, which markers mislead in trained people, how to control pre-analytic noise, and where a large chemistry panel stops telling you anything new.