Broadly the way material gathering works - with exceptions here and there for a few materials
G1-G3: easy, you'll pick up more than you can possibly use as you go along of almost all of them if you do a variety of activities
G4: you'll still pick up some as you go along but some of them are tricky
G5: really time consuming, except for a few which have easy routes to obtain.
Remember that G3 tends to give more than 60% of the benefit of G5, and G4 tends to give more than 80% of the benefit (especially once experimental effects are taken into account) ... and especially once you've levelled up the engineers you need more rolls to finish it off. So
- G3 = ~65% performance for <5% of the effort
- G4 = ~85% performance for ~10-15% of the effort
- three rolls into G5 = ~90-95% performance for ~40% of the effort
- maxed G5 = maximum performance for maximum effort
In my opinion, unless you have picked up a surplus of the necessary materials anyway, or are intending to do some PvP [1] where every last bit of performance matters, it's very rarely worth going past G4, and never worth maxing out G5 unless you really have no other use for the materials.
(Exception: a few G5 blueprints have a G4 raw in the "G5" slot for historical reasons, e.g. Heavy Duty Shield Booster - those you can pick up a lot more easily)
[1] Defining PvP broadly here as any activity where you're directly up against the performance of other players who will have maximised ships - might be combat, might be racing, might be trying to set exploration distance records ... maybe even some CGs if you're trying for "top 10" rather than "top 10%"
G1-G3: easy, you'll pick up more than you can possibly use as you go along of almost all of them if you do a variety of activities
G4: you'll still pick up some as you go along but some of them are tricky
G5: really time consuming, except for a few which have easy routes to obtain.
Remember that G3 tends to give more than 60% of the benefit of G5, and G4 tends to give more than 80% of the benefit (especially once experimental effects are taken into account) ... and especially once you've levelled up the engineers you need more rolls to finish it off. So
- G3 = ~65% performance for <5% of the effort
- G4 = ~85% performance for ~10-15% of the effort
- three rolls into G5 = ~90-95% performance for ~40% of the effort
- maxed G5 = maximum performance for maximum effort
In my opinion, unless you have picked up a surplus of the necessary materials anyway, or are intending to do some PvP [1] where every last bit of performance matters, it's very rarely worth going past G4, and never worth maxing out G5 unless you really have no other use for the materials.
(Exception: a few G5 blueprints have a G4 raw in the "G5" slot for historical reasons, e.g. Heavy Duty Shield Booster - those you can pick up a lot more easily)
Pirate Anacondas seem to drop these reasonably reliably for me.
Proto Heat Radiators are one of the easiest to get from HGEs, and trade down for the others. But the Heat-themed components are tougher to get than the others.
You can get lucky and pick these up from pirate Anacondas too - I got really lucky and got 3x3 off a single one, once - but it might take a while. That's where all mine come from but I don't do G5 drives very often.
[1] Defining PvP broadly here as any activity where you're directly up against the performance of other players who will have maximised ships - might be combat, might be racing, might be trying to set exploration distance records ... maybe even some CGs if you're trying for "top 10" rather than "top 10%"
