I can't speak for Dole Whips. But for most places they only have one cashier for walk-ups and the other 3-6 windows are for mobile pickup. It's to force you into mobile ordering.
For example, I like getting the soup or salad or mac 'n cheese in a separate bowl from the bread bowl at Pacific Wharf Cafe so the bread doesn't get soggy. You can't order it that way on the mobile app. So if I order through the mobile app, and go to pick up my soup, I then have to tell them I want the soup in a cup, not in the bread bowl. This sometimes is no problem and other times gets rolled eyes and heavy sighs as they shove the unsold food back on the counter and pour me my cup of soup. Therefore, I would prefer to use standby and order the soup correctly prepared directly from the cashier to avoid that extra step of having to send the soup back that they've already prepared for me when I tell the app "I'm here". However, with only one cashier at the location, each time I've tried, after about 20 minutes in line - with at least another 15-20 ahead of me - trying to do it "the right way" and order correctly, I'm starved and just give up and mobile order from the line, step out of it and go tell them at the next counter over to remake the order I just tried to place correctly but couldn't without a half-hour+ wait for my otherwise immediately available soup.
Another example - was there recently with a friend who wanted a meal at Flo's. Next available time was 50 minutes out. I said we can wait and mobile order for that time... oh, whoops, sorry it just updated and is now an hour... do you want to wait an hour for your meal? No? Okay, we can go wait a half hour in the walkup line and then get your meal, which is what we did and it how long it took, but only because they wound up with a line out the door and had to... I kid you not... ROLL OUT a portable ordering station for another CM to start taking walkup orders. I was shocked they actually did this. Still took half an hour though.
Another example - I wanted ice cream from Clarabelle's recently. Next available spot was 45 minutes. I walked over and got in line for the one cashier. Waited about 20-25 minutes during which time multiple other guests in the line told their families "forget this, it's not worth it, we'll get it another time, let's go" and left. AND they did eventually open a second cashier for walkups because again the line was going out the door. So I still got my ice cream before the mobile order would've been available without the line in that case.
So my best advice is - be flexible on your food choices and be prepared to either not eat when you're hungry, figure it out in advance, or wait in a longer time than ever in line for the one cashier working next to the six empty mobile pickup windows.
P.S. be kind to the CM's at the registers - they are even more frazzled by this than the guests as they get the first line of attack by starved angry guests and have no ability to change the system.