We often say in France that it's better to look at what part of the Louvre are of the most interest to you and only go to these ones. Even spending several hours in a row is no use as you will probably be tired in the end and won't appreciate what you'll see.
I too did this ... would not recommend trying to run through the louvre in 1 day. I was kind of "forced" to (only had 1 day and I guess a rare case of FOMO). Spend at least 2-3 days there. It's huge with so much masterpieces. The Mona Lisa was a disappointment.
I imagine the Mona Lisa is fantastic if you get to inspect it in close detail. Trying to poke your head over 100 flustered tourist, through a sea of arms, phones and cameras, is probably not the best way to appreciate it.
