This is just my opinion, but I really don’t like having sliders for program duration at all. Here’s why.
I’ve got a pretty typical residential irrigation system with a mixture of spray heads and rotor heads. For the spray heads, I’ve have multiple (short) run times to help prevent runoff. My run times in my programs are any where from 4 minutes to 20 minutes, and I occasionally make +1/-1 minute adjustments to fine tune those zones. There is simply not enough precision in the slider (which goes to 300) to make a +1 or even +2 adjustment. What inevitably happens is I try to bump the slider ever so slightly, and then it jumps by +6 or +13 (or whatever) minutes, then I give up on the slider and enter it manually in the text box.
I’d much rather see the little rolling wheel thingys (not sure what they are called) like are used for the start/end times. This would also support data entry in a MM:SS format…