When using bait gels such as Vendetta Nitro Cockroach Gel Bait for roach control you are not trying to just kill that one individual roach, you are trying to control the entire colony. Not all of the roaches are consuming the bait immediately. Many are picking little bits of it up and taking it back to the females hiding in walls and appliances to feed them. The roaches you see out in the open are only at max 10% of what is actually there, so you need the IGR to start being absorbed by the roaches and to start effecting the population as a whole so that they are unable to reproduce until they die from the bait or any spray you may be using as well. Baits are also not going to kill the roaches instantly once they consume it, so in that time frame until they die you do not want to risk allowing them to continue to mate and reproduce faster than the bait kills them. 

One box of Vendetta Nitro Cockroach Gel Bait will not be enough to eradicate roaches in every room of a house. If you have multiple rooms and the home is severely infested so that you are finding roaches everywhere even during the day, then we would recommend getting our Commercial Roach Control Kit so that you have enough product for several treatments of all areas. This includes a powerful roach bait gel, Temprid insecticide concentrate, Gentrol IGR (Insect Growth Regulator), plus a bait gun. Keep in mind that a roach population of that magnitude did not come to be overnight, so it will likely take months to competely eradicate them. You may also want to consider first using foggers as a cleanout, such as the FMC Pyrethrin Fogger. You would then need to clean out all the dead roaches before following up with the products in the kit. Please also review our Roach Treatment Guide for more tips and information.