And there is a small savings in cycles using the slotted method that has the down side of requiring an interrupt that may run longer than I would like and can be delayed by serial print.
Yeah, it may be practical for a small number of delays...
I have nothing against the slotted method. I just don't see any significant advantage over using count-up (what's behind the BWD method) by using count-down (what's behind the slotted method) when I take -everything- required into account.
Consider that in addition to decrementing slot counters there needs to be a zero check first as you don't want a counter to roll back, do you?
Not needed, look at the type of array and at the logic.
Then you trade off speed for measurable duration, in this case you halve the maximum interval to 32.767 seconds. For a whole lot of things that is acceptable and you can go to 32 bit signed values and get a bit less than 24 days if need be.
Both ways have applications where they fit better so IMO it's good to know both.
The slotted method is an array-adapted version of single-timer ISR timer solutions I have seen here already so if I don't act like it's big news then please forgive me.