If you're like me and don't turn off/reboot your computer often - you may notice, if you have more than a handful of plans, that the timelines displayed when you use the Plans -> Manage don't update.
Although opening a plan will cause evemon to recalculate the skills and timeline.
It's more of an issue when you have plans that contain related skills that you've recently trained. If you stop and start evemon - then it'll recalculate the duration of the plans and the timeframes it displays will me accurate again.
I usually create a master plan when I'm looking at a new ship or mid-term target - and then from that break out parts into smaller plans (ie supporting or gunnary skills needed) - you can (and I often do) end up with a handful of plans that all require the same dependancy - which I'll train up first.
When a chunk of skills have been trained - if you restart evemon these plans are suddenly complete or be almost complete - which is a nice surprise
