Sure, they require reaction. A plan itself isn't built on a reaction though, they 100% guaranteed have a set plan for themselves that they adjust accordingly. To say that Nintendo doesn't know what Nintendo is gonna do is, again, crazy talk.Most of the reasons I listed, Involve Reaction to foreign situations that change day to day. (Sony/Microsoft talking about Next gen, Coronivirus updates, etc.)
Like yeah, Corona has influences (production mostly so far), saving big hitters for E3 is a guarantee (although at least some would definitely be teased before like Smash), General Directs are very much still a thing and there's 0 reason to assume otherwise.