Then I would use a radio test multiple frequencies on the FM, AM and SW band and then use a couple of cellphones to the GSM and UMTS bands. You could even use a small TV and test UHF and VHF bands. I would say that after such a test you could be fairly sure you were covered.
The problem is both frequency, and dynamic range.
You may think you have a good Faraday cage using receivers but you could fall well short of performance because the signals weren’t strong enough to show your true performance under EMP conditions.
It’s better than nothing - but it’s also a false confidence builder if you get a radio to block a station.
It’s a matter of how sure you want to be. The best inexpensive ad-hoc shield I can think of is the trash can - but use steel wool fragments around the full circumference of the lip and hammer it down solid with a rubber mallet.
No guarantees, but it’s much simpler in its uncertainties than this cabinet thing.