At first I thought this mess was all the fault of TiVo, but KOMO 4-1 changed their physical channel from 38 to 30 and pulled it off without a hitch, so there's evidence that KING 5 and KIRO 7 may have done something different that didn't work so well.
There is a huge number of steps and variables in the repack process, and while all the stations in the location (even those not moving(*)) have to evaluate the same criteria, not all stations need to perform the same steps. And schedules sometimes slip, too (weather happens, or at least I have been told weather happens, in the greater Seattle area
), making the best intended plans be something else. There is a report commissioned by the FCC that evaluated many of the steps that a typical station would have to do (it was used to estimate the costs to the station for the repack). Not surprisingly, the report had easy, average, and hard issues identified which would depend on the location (I believe Sutro Tower in SF was used as the poster child of being super hard (I think they just wanted to use the photo of the tower poking above the clouds in the report)). So, yes, differences happen.
(*) Typically stations share a tower with other stations, and if the other stations need work done on that tower, that may force a station to use alternative transmitter facilities or go low power for a period, as a matter of safety of the workers on that tower.