Of course I can't comment about other player's experience.
But for me farming G4 and G5 mats with destroying ships works pretty reliable.
You can't get all types, but what you can get are
Core Dynamics Composites
Exquisite Focus Crystals
Imperial Shielding
Improvised Components
Military Grade Alloys
Military Supercapacitors
Pharmaceutical Isolators
Proto Heat Radiators
Proto Radiolic Alloys
No Biotech Conductors that way.
You can get a lot of G4 stuff such as
Chemical Manipulators
Proto Light Alloys
Refined Focus Crystals
etc etc etc
G5 mats drop - if they drop - usually as one giving you three. I would say every second to third Conda/Vette/T10 drops one. I'm in Fed space hence Cutters are extremely rare hence can't comment on its drop rate.
G4 mats drop usually at two or three (6 or 9 in total) and often you find two, sometimes even three types. In total about 9-15.
I fly a lot of missions. Many of them data delivery, cargo delivery or source and return. And I usually stack them so running 5-10 at a time.
Almost all of them being Elite level and at least the half with enemy warnings.
On top I stack whenever possible with pirate lord assassination missions, that way you get a very high chance you end up with either a Conda or a Vette.
Mission enemies come in packs of 4 so if you killed one another three will come.
Pirate lords usually the main ship, rarely a wing mate.
From my experience the higher level enemies you get when accepting missions from L-pad stations.
M-pad ones often let you end up with FDLs, Pythons, Vultures and Mambas which don't give the higher grade stuff.
Now what you need to do is storing a few tons of high value stuff with you, the usual 5-10 tons of gold, palladium or whatever.
That way you do not only attract the mission assassinators and pirate lords but also standard pirates.
When you jump around, delivering or collecting commodities you don't deliver straighforward but you fly relaxed in supercruise and wait for the assassinators/pirates to interdict you. Very rarely I need to interdict them.
If you are unlucky two of them interdict you at the same time and when you submit you land alone in the instance.
But if you are lucky and get the usual comm messages from more than one and only one interdicts you (90% of the time) you land with one of them in the instance and have a good chance that another one - could be a pirate, could be a mission assassinator - drops into the same instance. Best case (two times) I had so far 4 in one instance, but 3 already is pretty rare and with 2 I'm more than satisfied.
If not more than one, just take out your prey, get back into supercruise, wait for the next, rinse and repeat.
I believe the key is to combine different missions, stack them and being well armed.
Also note that normally I don't run that way for mat farming but for running missions and the ship farming is done en passant as a consequence of the mission choice and my cargo.
Though additional value cargo is not a must as mission assassinators attack you regardless of whether you are carrying goods or not. Accepting a mission and flying around is enough.
Value cargo just attracts normal pirates on top which for the purpose of mat farming gives additional chances. Some of them unfortunately low level ships hence not always worth to try it.
2 cents.