It's always a good idea to hoard materials, depending on the amount of time you play and resources you can reasonably obtain, it is good to have at least a couple thousand of each resource. With that said, while I understand you like doing things "the old fashioned way", you are going to end up spending a LOT of time getting this amount of resources when there are definitely more efficient ways to get materials (that will probably be more fun as well). The reason I would say you want at least a couple thousand is because planetary materials are not only used in many exchanges such as infusion, but they can be used to purchase glimmer from Spider (changing to Rahool) on demand when you are low. My recommendation would be to farm Dares of Eternity and complete the Starhorse bounties. If that gets old, you could also play Strikes or Crucible. Essentially you want to get a lot of legendary items to dismantle for legendary shards. Just remember not to farm for Etheric Spiral, this resource is going away in Witch Queen.