Multiple paths to the same Relic would be possible.

Part of it has already been done in previous Relics. With stuff like Light farming where you *Could* go farm Tam-Tara solo for light. But you *Could* also go do Alexander or Bahamut raids too.

To say nothing of the fact that much of the Relic quests are gathering specific items. Who's to say you couldn't gather those specific items from multiple sources? Such as getting drops from Raid bosses, grinding Dungeons for Tomestones, farming Eureka for Crystals, crafting them yourself etc.

As for a time difference between the methods... Artificially time gate them. Say, you can only obtain X amount of Y item per week. So, irregardless of method, you will only progress at a specific rate per week.

If this is even a problem. Since, while people might complain about how certain ways are more efficient than others for farming out the relic... The fact remains that they don't need to be the most efficient... Given that the steps only unlock when the patches come in and otherwise it's far quicker to get equal item level stuff from non-Relic grinds to be able to participate in content (Such as just buying one from a Tomestone vendor)

Relics have always been just for glamour given that, while yes, there are times when they're BiS, but for the most part, you only complete the thing at the end of an expansion because that's when the final stage gets added to the game. At which point you've likely done all of the content anyhow and just want to grind out the shiny relic for glamour.