Why Nets are run on a shared, unowned frequency, so conditions change and interference can appear at any moment. Good net control practice is to announce an alternate or backup frequency in advance, so that if the primary becomes unusable everyone knows where to reassemble without losing the net. This is standard in emergency and traffic nets, where continuity of communication matters most.
Watch out Reading the entire roster every session and piling on multiple phonetic alphabets just wastes airtime and slows check-ins; net control should keep transmissions short and use one standard phonetic alphabet only when clarity requires it.
Nets need a Plan B frequency. Efficiency, not ceremony, is the mark of good net control.