Hi, very new user, started last week. I have very similar situation to Viking. I am unsure of my plan for the same reasons. I want to improve my 10min and I unfortunately have 8h. I don’t see why I would adjust my objective, for ex 10 vs 6min. I’m still hoping the system will tell me what I can achieve in 8h, if it is only 1w over the winter, so be it I guess.
That’s what I would do. Set an interim goal for a date in the spring followed by a 1-2 week lull then set a Goal/Event/Race forecast for August.
I’d have a hard time following a single forecast plan for 6-10 months or longer.
Consider that a standard Base-Build-Peak progression on XATA is 120 days long. That means you can literally go from sitting on your couch to a peak fitness level 4 months later.
XFAI provides a more nuanced approach to dial in particular targets with options like Readiness for an event or race. However, my attention span to stick with a mapped itinerary month after month is limited. 
Another option is a XATA phased progression to get ready for Spring Time followed by a break period, then schedule a specific XFAI forecast for a target event in August. That’s how I’ll be using XFAI. YMMV
