Out of 26 anime which fit this criteria, 21 were the same overall rating as the first episode's rating; in other words, when you watch the first episode of an anime, over 75% of the time it is representative of the future content. Looking back, while I didn't calculate it in the same way this seems to have been true for the winter 2016 season of anime too.
In the spring 2016 season, out of 15 anime with no fanservice in the pilot only three showed fanservice in later episodes, and all three were upgraded to Low, not High or Obvious. Those anime which began as High or Obvious did not change their rating, though the second episode was sometimes devoid of fanservice entirely. It looks like creators are far more comfortable increasing the levels of fanservice than decreasing them for longer than an episode at a time.
I rate for fanservice sensitivity. This means that anime which are completely fanservice-free except for one moment which crosses the line will be marked as Low. This season's Kuromukuro is an example, with a man squeezing a woman's breast in episode three changing the None rating of the previous and subsequent episodes.
Rating on the side of fanservice sensitivity also means that anime which are completely fanservice-free except for one female character's implausibly revealing costume will be marked as Low. This season's Endride is an example, where I was very tempted to put None, but erred on the side of rating for people who might want a heads-up that occasionally they will be face-first with underbutt.
Even with such strict measures, this season is full of anime with no fanservice whatsoever, as shown on the table below. If you want a quick recommendation, my likely pick for best anime of the season is Kabaneri of the Iron Fortress, pictured above.