The burden is calculated very simply: Avg No Beats/hr/Avg No Irregular Beats with the average computed using the entire data set, all hours you were on the monitor. The technical definition is 'the longest run of AF on any one day during a 30 day evaluation.' Well, nobody I know wears a Holter for 30 days, or lies on their back during a horribly long ECG somewhere. So the Holter is a best guess, but based solely on the 1-7 days that he/she is likely to be asked to wear one. The burden calculation is therefore always an extrapolation out to 30 days.
https://www.ahajournals.org/doi/10.1161/CIR.0000000000000568