I have had a recent increase in pillager patrols near my homestead. I did burn one of their outposts to the ground and left behind a bunch of iron golems, but the nearest village is about a quarter of a KM away fron where I live. Do they set up camps? I had 2 patrols in just 2 days.
The pillager outposts will continue to spawn pillagers even if the tower is destroyed. The only way to stop the spawns there is to either cover the 71x71x71 spawning spaces around the outpost with slabs or water. As far as patrols are concerned, they have a chance to spawn every 10 minutes or so. The patrols can be stopped by lighting up an area. The patrols will not spawn if the block light level is 8 or above. Even during the day, without player intervention, block light levels are usually low, so patrols can spawn.