This is a great question, @matt.
My thinking is that the Savings Budget/envelope/rollover approach is designed to level out month-to-month lumpiness by pushing favorability & unfavorability forward. If you have unspent favorability in an expense category, you will have more budget available the following month to fund a postponed purchase (for example).
In the context of a delayed purchase, I think the existing implementation where the previous-periods savings inflates the available expense budget for the current month makes sense. If your budget values are accurate for the year, the favorability is likely shortlived (once the latent expenses come due). Reducing your expense budget based on previous-period favorability doesn’t make sense (to me) in that context. Essentially, you are expected to spend more the month after favorability because something you budgeted for is yet to hit; the result is more expense budget and thereby net cashflow unfavorability.
That said, I’m not expert. I’m open to reworking the implementation (and republishing the master) if you believe there are more intuitive or better ways to display the data.
Best,
Randy
P.S. Curious for your thoughts on this too, @cculber2.