Can you learn things about your job in XP parties which will be used in EG? Yes, anyone would be a fool to deny it outright. However, most things that can be learned like this should be able to be picked up fairly quickly in my opinion. Nothing, and I mean nothing at all, should take anyone the amount of time it used to take to get from 1 to 75, for a person to learn, understand, and develop the necessary skill to perform something you can learn about your job. No matter where you put it to use, it should never take that long to learn it, or get good at it.

I think if you were active the full time, 1 --> 99 in 3 days would be fine, so long as the person has to participate in the party and do their part. If they had to, then things would be easy to learn in that time frame, skill ups could be accelerated to accommodate that speed of leveling, and all would be fine. The parts you learn are not things that take a super long amount of time to learn, maybe for you to become skillful at, depending on what you are talking about, but not ever something you take that long to actually learn.

That's my take on this argument at least.