It means that the carrier has to make sure there are no major bugs in each update release. The schedule is usually the manufacturer that releases an update for a particular phone gets worked on first, and most carriers can't do more than a few phones at a time. (It's not a job a single programmer can do in a week - or a month.)
Of course you could get a really fast release - of bugs, like LolliFlop. There was a memory leak in 5.0 - which eats memory and battery. It wasn't fixed until 5.1. So if you're waiting for something worth having, Verizon isn't going to be releasing it for a LONG time. (And, as far as I'm concerned, LolliFlop should have been a minor point release of KitKat - there are no major changes, except for looks and sizable apps.)