BTW, Marshall Newhouse was not a "lemon". He played 10 seasons in the league and
started at left tackle for 13 games during 2011 season when the Packers went 15–1. Newhouse continued as the Packers' starting left tackle for all 16 regular season games and 2 playoff games in 2012
per the Internet.

He played in 133 games and started 81 on them. For a R5 pick, that's pretty darn good.

What you're calling a lemon is actually a league-average 'C to C+' player at worst. That you think he wasn't very good shows what you consider average to be. Lining up 5 UDFAs to basically be fat, slow and unathletic shock absorbers won't protect a QB against a good pass rush, and it sure won't open holes for a run game. It would actually be worse than 5 Newhouses. It would be as bad if not worse than 5 Jake Hansons or Royce Newmans.

You can absolutely find value at OL in Day 3, but league wide those guys are much more likely to be subpar or outright failures. GB has been above average in developing OL players for a few decades now, and some here clearly underappreciate that.