It depends on your frame of mind. Want G5 mats, you can get them:
By doing missions! As you said, credits are easy to come by so forgo that big reward and take the mats instead
When exploring. Instead of just honking, and just scanning the planets, scan for FSSs as well - any HGEs that pop up and are close by, drop in and get the goodies. Or if you see a CZ or REZ, drop in there, always a good number of mats floating around.
Heck, even mining! I wonder how many have the raw mats excluded when mining ...
Also, I think too many are fixated on finding a specific mat and ignoring anything else and they forget that mats can be traded and exchanged. Yes the exchange rate is abysmal but you can use the mechanism. I also wonder how many will go out and grind mats to engineer a module that they already have sitting in store or on another ship they don't use and have no intention of using again (i.e. they have forgotten about it or what modules it has).
Finally, how many will engineer to a G5 level, but not realise they could have stopped at G4 and they wouldn't have lost much in capability? They could have used that time they saved in well 'GIT GUD' training
As for getting around, yes it can be a chore but I took the approach that I was getting to know my new ship. Recently decided to get a Mamba and fully kit is out. Since it is combat focused the jump range won't win any awards but I had a great time making my way to each engineer so I can not only engineer but also get the experimental (which often make or breaks the engineering improvement right). Along the way I got some mats, got to try out the modules pre and post engineering so I knew the difference and could appreciate it.
Having said all of that, the process is down to personal preference. If someone has decided that not only do they need their new ship RFN, but they also need to have it fully engineered RFN, the entire game will feel a grind and worklike.