Doesn't seem like the most efficient
Just play through the campaign, quests, weekly, daily, challenges and content naturally and see where you end up
Well, I completed the story missions. Light level 209. I feel like that is kind of low... wearing nothing but blue gear except for a level 40 side arm.
Most people are completing the story and quests and ending up between 220-230 light level.
You will need legendary marks not only to buy items, but infuse others.
I don't understand why you keep defending the changes to the mark economy. They drastically reduced the amount you can hold and earn. How is that better?