The estimated runtime for a biofeedback scan is fairly accurate, where the final time to completion is governed by your actual resting heart rate and whether or not you can avoid data read errors.
However, a scan from 76k to 152k, at a step size of 20, is only 3800 scans, and is roughly 63 minutes, usually closer to 70. One also must take into account the start up delay time and ensure single scan is checked.
If one forgets to enable the single scan option, then the scan will perform a series of followup scans and it will take nearly 2.5 hours.
I actually forgot once, and learned the hard way.
If you are getting 308 minutes as your estimated runtime, then one of the values you have entered in for the scan is not correct.
It may be as simple as a decimal point is added, etc.
Please go over and verify that the settings look similar to the following.
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