I live in a fairly dense suburban area. I've got neighbors on 3 sides of me. We all have pets and share the same concerns regarding fleas, ticks, and similar critters.
Together, we decided to spray the yards at the same time so that we could rid the largest area and enjoy the longest period of relief from these pests. One application to all the yards has kept the bugs away for an entire season.
Everyone is happy and I'm sure that we'll do it again next year. It also took care of grubs, ants and other undesirable insects.