ADHD meds and monthly cyle

At what point of your monthly cycle do you notice your meds don’t work as they usually do? Are you noticing this with stimulants as well as non-stimulants? I take both and have started to notice that once a month my stimulants (Vyvanse) sort of stops working but there is no change in the non-stimulants’ function. I haven’t been able to predict it just yet and am taken by surprise when I am scatter-brained at work in front of clients!