I've seen commentary in a few different places about this 100% sign being part of Lumon being unnecessarily extravagant/showy, because no one would be seeing this sign, it's literally ABOVE all of the characters! It is very funny, and I love that thought and agreed with it completely when I first heard the idea.
But, I've since changed my mind. This is not superfluous, and someone definitely would see it: The cameras. Lumon. The Board.
I think Milchick planned this specifically as a way of showing how dedicated, hard working, and effective he was as a manager. "See this sign, Board members?? ONE HUNDRED M'FING PERCENT!!!"
And then, like most of his efforts for this company, it's for naught and everything goes to shit.
Quit this job, Milchick. I can't wait to see your redemption arc.