So far in the last week I've flown 14 segments on UA and was provided the full can on all the longer flights that my upgrade didn't clear without having to ask. A couple of times they asked if I wanted the whole can but otherwise it wasn't a problem.
As a side point, one of my flights went mx yesterday in LAX that would cause a miss connect so UA happily rebooked me on DL LAX-ATL-FLL. Being in E- on DL we didn't get the whole can on either segment. The cups appeared to be bigger though. Not sure if they were just taller and narrower with the same volume, or if they actually were larger. We did get pretzels, peanuts and milano cookies though!