MSEA Ver0.86 Patch Notes

Except there's more factors that go into part exp than just "110% bonus!".

Not everyone is going to be killing at the same speed as you. Not everyone has the same skills as you. Not everyone will be able to fill that ideal standards you're trying to put on them. Party training can go well, provided you reach the ideal criteria you're talking about. However, you're taking a gamble every time you train unless you're training with close friends who love grind4lyfe at the same pace as you for hours on end.

[...]

Well actually the new party exp formula should be better in this case (training with other misc / weaker people).

Now its something like (correct me if I'm wrong on this one, don't know the 100% correct actual numbers)
- 70% of the exp goes to you. (105% with HS)
-- 40% of the exp comes from your (lazy? / leeching? ) party member. (60% with HS)
-- Total 110% exp. (165% with HS)
- 40% of the exp goes to your (lazy / leeching? ) party member. (60% with HS)

The new formula is like:
- 90% of the exp goes to you. (135% with HS)
-- 20% of the exp comes from your (lazy? / leeching? ) party member. (30% with HS)
-- Total: 110% exp. (165% with HS)
- 20% of the exp goes to your (lazy / leeching? ) party member. (30% with HS)

So it's actually "less risky" to train with other people, exp wise.

Besides that, training with other people in the map -killing monsters- increases spawn too!