When you go to an inspiring event like a conference or meetup you gain this surge of energy. It’s amazing what you can do while you’re riding this wave of inspiration and getting things done. Over time this energy lapses and you approach the level you’ve always been at. If you go to less than one event per year (estimate), this surge of inspiration has negligible impact on your overall energy and accomplishment. If you make a point to intentionally be around inspired people, however, these surges of energy make up a significant portion of the year, raising your average.
I haven’t tested anything directly, but I suspect that an event to keep your energy topped off doesn’t need to be a crazy multi-thousand dollar conference with big keynote speakers. I suspect that it can be a workshop or design spring with a small and engaged group.