Great question — answering as the UphillTech team:
I know this question is really old ... but for anyone stumbling across this: Google has a limit as to how many hits per session they allow. As of today (march 2021) the limit is still 500 hits per session. https://developers.google.com/analytics/devguides/collection/gajs/limits-quotas So if you trigger an event every second for a 30 minute video you'll be sending 1800 hits for that one audio file alone.
Full answer by Daniel: https://webmasters.stackexchange.com/a/133540 (CC BY-SA 3.0).
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