4 guildleves in less than 1 hour=1/3rd of the way from 49-50?

[NoctisUmbra]

And how many leves can you do in a day? 8? Right.

Day and a half actually, to further press this point. One out of every three days doesn't have a reset.

How long can you run grind groups? As long as you want?

You can get from 46-49 in a matter of 8 hours (in 1 day) with a continuous grind party whereas you can only do 8 regional leves every 36 hours to get less than a rank's worth of sp?

Yea, no. Party grinding is still the focus of this game.

Leves have higher sp/hour, but that alone is meaningless since they are capped. In fact, they have higher sp/hour for that reason. So a casual player can log in briefly at their own leisure and still stand a chance to get some decent amount of sp.