It seem I wrote that less carefully than it should have been. It means you can do little else in addition to whatever normal stuff you are doing for your occupation, community, etc. So only one skill can be trained at a time, and you can't take on any tasks above your allotted "adventuring time" per season. So if you train a skill, that's your "extra activity" you can do that season above and beyond your "adventuring time". 
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