You'll probably think my testing regime is authoritarian but you'll have to basically swoop down and test public in all sectors, rural, urban, white, black, hispanic, asian, etc., all ages. No recruitment but just grabbing people off the street and in the hospitals. And test hundreds of thousands. You are going to have biased data if you try to recruit people in because of varied motivations of those answering ads. Yeah, that costs money and probably a lot of it but if you want viable results, that's what you will have to do. And yes, you better have viable testing that passes legit QA/QC practices. If you don't have rapid turnaround (i.e. less than 12 hours), you are going to be playing catchup on the data and always be behind.
Think of it like indoor air testing. You can leave Summa canisters in place for 8 and 24 hour periods to take a quick snapshot of indoor air conditions for opposite seasons and it will give you an idea or, albeit at greater expense, you can perform continuous air monitoring which will identify intrusion sources, peak times of increased air impacts, and then pinpoint the facts and properly mitigate.