I encourage the kids to walk as much as possible (mine are all 13 mos to 3.5yrs), BUT I make sure I have a way to "contain" them all for safety reasons. For example, unless I can really trust a child (which I can't currently do), they ALL need to be strapped in at the bus stop. There have been times when I've had to get on the bus to physically get a reluctant child off, and I would not be able to safely leave 5 toddlers on the sidewalk to do that.
I also have tantrumers that could make a 5 minute walk take MUCH longer
. I use a Choo-Choo Wagon.
We do 1 - 1.5 hour walks (in addition to bus runs) at least a few times a week.
Imo, I would just make sure you have containment for all of the less-than-predictable kiddos.