That's why I wrote "rule/principle". I should have added "suggestion" - at least I did in spirit. Also, I think you misread what I wrote. The error in the Adventure Book is in the description of the second scenario, where it is stated that it takes place "less than a season after" the first, while if you follow the suggested timeline, it takes place more than a season after the first. It's not a big deal, it's just an error.
Yes, the "one adventure per season" suggestion does need somewhere the PCs can spend their downtime, some sort of local connection. Or they could just hang out at an inn in Pavis or something, I guess.
I also agree on the "experience rolls after each adventure" (as we always used to do it in RQ3) rather than strictly "once per season". So, the point is: RQ:G emphazises the need for downtime more than, say, RQ3 did? That's good, I think. And I look forward to seeing how my players will react to being "sent back" to their community for some OL (ordinary life).