Would you focus on the main quest and end up being underpowered during one of those difficulty spikes or grind with side quests to slowly level up and risk losing interest in the story?
Being a completionist (and due to my OCD), I often try to touch every possible corner in the remotest areas of all available levels, but that soon feels repetitive, I lose interest or even forget about the main story. Also, reality is always waiting to pull me towards the "grand scheme" of things.