All construction permits except LPFM, expire automatically after 36 months. That is standard language. There are very few exceptions to the automatic expiration. One is if some situation beyond all control of the licensee occurs that prevents timely construction. An example might be that the local zoning authorities block all attempts at construction. A natural disaster like a broken dam, volcano or hurricane could also be grounds to ask for a temporary extension. Sometimes, a late sale within 180 days of the end can gain a short extension if the FCC is asked for such a waiver in a timely manner. In the case of WURB, the clock is ticking and it'll be interesting to see if anything comes of it. I have my hunch, but I'm not saying....
Regarding the Chiefland translator, I don't think there was any reason to wait. The application to change channels would have had priority over LPFMs by its earlier filing date. Clearly, 93.3 is a fairly busy channel. If it were my translator, I'd be pretty hot to get off of that channel. Has the local response to it been good?