How frequently do you see cockroaches in your apt (by city)

5th floor apartment. We see one about every 3 months. We did have an infestation in the space between our apartment and the one above and they came in through the fan openings in the bathrooms. We put mosquito netting over the inside of the fans and it stopped them. I’m also convinced some monster size ones arrived in cardboard boxes we used for shipping and from IKEA.