Engineering Progression

I've sort of hit a wall in combat, it doesn't seem like my Chieftain does enough damage in Conflict Zones, (pretty sure enemies are tankier but that's not the point)- and I wanted to make it "usable" across all combat content

I finally made it to Deciat and Farseer after several incidents involving Cargo Hold malfunctions from impatient star refuels and a bounty that I had some issues becoming rid of. I found out that engineering is like, tier based and that I'll have to build crummy upgrades to use the next tier even after increasing Engineer Reputation with trading or selling maps (right?)

Here's my question: If I stock up the resources to build everything once, come back to unlock higher tiers, will I be stopped from doing that and "maxing" the engineer somehow? I imagine there's a build timer, but is there some sort of extra fee for re-engineering an FSD several times or do I actually need to make previous tiers several times to unlock the next one in the grouping?