One roach means fifty.
Roaches are nocturnal and thigmotactic — they hide pressed into cracks all day and only forage at night. A roach bold enough to stroll across your stove in daylight is either overcrowded out of its harborage or starving, and both mean the hidden population is well past the early stage. Daytime sightings are the red flag, not the night ones.
The egg case is why one-time treatments fail. A single German roach female carries an ootheca with thirty-plus eggs, and the case shrugs off treatments that kill the adults. Kill the adults, skip the follow-up, and three weeks later the next generation is foraging your kitchen. The second visit, timed to the hatch, is the product — everything else is setup.
Canton’s older housing stock gives roaches exactly what they want: gaps around plumbing penetrations, aging cabinet construction, shared walls in multi-unit buildings, and damp basements. The treatment handles the population; the sealing and sanitation guidance handles the invitation. Do one without the other and the building re-seats itself by next season.