Waiting until you want to Engineer something before starting to collect the materials is a pretty "Normal" mistake to make.
I can tell people "dont grind, collect as you go" as much as I like, but its not the answer they want so ignore it.
Yep. The only exception is when you're first discovering engineering and think you have to have everything G5'ed, I made that mistake myself so I know of what I speak. The only thing I really "needed" was to buff my FSD for more range (to make it easier to get from point A to point B, that's all), and getting those mats before I learned, truly, just how many places you can collect them and trade to others if they're not the ones you're looking for was, indeed, a grind. But it was all my own fault because I felt that I "had to" G5 everything.
All you "have" to do is to get your access to G5 with your preferred engineer so you can pin the blueprint and use it wherever. After that, every G you add as you gain mats is not a "grind". And, truth be told, there aren't really that many upgrades where you really need G5. G3 is more often than not good enough until you find that you have mats to spare through the "collect as you go, trade when you're full on anything" method.
Honest question: how does this "collect as you go" approach work, exactly? It's not like materials/data are lying around everywhere in space, are they?
Yes, they are. Manufactured mats drop from every single ship you shoot, make a habit of collecting them. Even a 1 class collector limpet controller will make that dead easy, especially in a RES where nobody will shoot at you unless you shoot at them first. Also, every single signal source will have some. Don't ever ignore a high grade in a system you're passing through. Even if the mat you get isn't one you're looking for, you can trade it to something else.
Encoded? Scan every single ship you see while you're just being bored in Supercruise anyway. Again: Trade if you run full on anything. Also, installations. Get a recon limpet controller, learn the silent running before attach, disengage after attachment, re-engage after hack completion for a few seconds, you can do this in ANY ship, get free encodeds without aggro/bounties. Trade if you run full.
Raws? If you don't mind the trip, go to a shard site, fill up on all the G4s, go back and trade for Selenium or just make a habit of surface prospecting on every planet you find that has it.
Just make a habit of that, and you'll soon find yourself inundated with messages that your bin is full and then, if later you find you want to upgrade, you can remote engineer because you surely pinned the print, right?
Oh, and make a habit of adding the experimental you want at G1, not when you're at G5. The experimental you can only get with the engineer, and it doesn't matter if it's G1 or G5, , but the G5 you can get at ANY station as long as you pinned the blueprint.
There. Easy.
But if you're "racing" through every system, "collect as you go" won't work.
If you see a 20$ bill on the sidewalk, why not bend down to pick it up? You may not need it now, but it might come in handy later.