I think one of the reasons this release was out was so fast was due to the crossbow issues many of us were having where the mode would start and end before the ball could be launched due to switch issues elsewhere. A few of us had discussions with Lyman over it and he rushed this out to address the bug.
Stern has multiple programmers working on multiple different projects at the same time. It should be expected that game A updates don't impact game B or C. Frankly, TWD code wasn't that great for a long time. It's just recently that it got great. WWE and Kiss owners, you haven't waited nearly as long as us TWD owners waited. Plus TWD update 1.56 didn't contain anything that would require the licensor to approve. Who knows what's coming in Kiss. For all you know it takes them 2 months to give the release ok.