You make a lot of assumptions. I'd stick to what people actually say and ask if you're unclear.

The most time intensive-thing about grids in general is mlb'ing all the related wpns from that event.
MLB'ing weapons doesn't take long. Maybe an hour for Advent and Union events? It's mostly just time going through the menus. Raid events are a pain, but they're about to become much less time-consuming. Honestly, I usually spend most of my gameplay time on Accessory Quests and related drudge work. Besides that? Just navigating the terrible interface.

Why would I farm weapons for elements I don't need? Just to keep my options open mostly. Also, most events give useful rewards besides the SSR weapons.