Honestly you might already have the materials needed. People that complain are mostly after perfect modification - they need lots of materials and luck. I never needed more than 5-10 rolls to get a very good result . Those you can achieve without grinding specific elements and you might have already in pocket. You might need to visit a planet or unknown signal sources several times, but nothing that can be defined as days or weeks.
Also remember that G1-G4 level engineering you can do with easily accessible materials and they offer significant boost already. You might not even want G5 at the end.. Just give it a test, nothing to lose or fear about.
And to get FSD maxed at level G5 it's easy, if you have no other engineering mods. Some people here mentioned that RNG gets nasty after 1st modified module and my experience is the same.
Yep, no point grinding for the god roll unless you really, really like that sorta thing.