Some of the early sites do not have everything ready to do make 3G and 4G LTE live now. Depending on the reason why, it may require a second trip, and sometimes they don't. However, Sprint and the OEM's decided instead of delaying the start of Network Vision, it was better to get started and re-roll a second time (where required).
Most of the NV sites where 3G is live, but 4G is not, is related to backhaul delays or the 4G cores not being ready. And in some instances, it is site equipment related. Where 4G LTE is going live, but 3G is not, is mostly related to cores not being ready at Switch centers. In cases where 3G/4G cores not ready at DDC's and Switches, re-rolls are not likely required. In cases that are backhaul/site equipment related, another truck roll will be required.
By mid summer, in most places 3G and 4G will go live at each site back to back, as most of these issues will be worked through. This is a much smarter plan then waiting to start NV mid summer.
Robert