I’m on the same page here with this 👆🏻user. I can’t believe my eyes that somebody’s I-751 is taking THAT long - 3+ years with no action taken, bizarre. This should not take so long.
In most cases filing for N-400 does help, at least USCIS currently moves faster with naturalization and mostly grants combo interviews. My immigration lawyer calculated the dates for my I-751 and N-400 filing right away and did not advise in any way against filing when becoming eligible so I certainly won’t wait, filing this October.