Gone in two days is really unrealistic scenario for dealing with bedbugs. They're much, much, much more resilient than that. They can go months without eating.

It's not really a difference of opinion that it's unrealistic to believe to be done with them in days. It's just not gonna happen. Bedbugs are resilient as all fuck and it'll take quite some time to know if you're done with them or if some managed to survive. It might be two months and you'll find one bugger has appeared in a bedbug cup. They're insanely annoying shits.