I had a good week last week. I got one on Tuesday, one Wednesday, and two Thursday. But none so far this week. I've seen what is probably the same squirrel the last two days. It runs as soon as I open a window, however. I might have to go out the side door and come around the house. I put some corn in a bowl on an old table in the area of the yard I've seen it. Maybe that will tempt into sitting still long enough for me to get a shot. My dog sees them on that side of the yard first but the wary ones will go to the backside of the tree once I show interest - even before I open the window. But it will mess up. They always do. I've shot 13 since squirrel season started in SC in October. But I didn't start getting them until the leaves fell in November. The smallest was 4 ounces and the biggest was a pound. The 4 ouncer was very unusual but I've shot several in the 8-9 ounce range. Most are 12 ounces or more, however. I use a fish scale on them before cleaning. The hide comes off the smaller ones a lot easier than the bigger ones.
I am in maintenance mode. I retired last April and started knocking them down when they homesteaded my loft. At first it was a slaughter fest & I was killing several a week & it wasn't unusual to kill 2-3 in a day. As the months went by there were fewer and the sightings less. But at times 2-3 will move in. I may go several days without a sighting but the dog & I keep looking

.
I expect the population to rise again in the spring and summer as the various fruit trees in my yard start to produce. They are an absolute magnet. I just about have to camp out in the yard to fight them off the fruit

. There is a smorgasbord of trees around my house such as pine, oak, black cherry, southern magnolia, spruce, holly, china berry, pecan, & sweet gum. So with the many varieties of fruit trees thrown in, there is no shortage of food at anytime thus the huge attraction to the pesky squirrels.
They also move into the free nests (dreys) constructed & left behind by the ones I have sent to the happy hunting ground. LOL free housing.
So it took about 6-7 months for me to get to the point I am at now. As you mentioned & many of us have experienced, the squirrels in a municipal setting when subjected to continual hunting pressure or repeated predation shortly become as
wild acting as the ones in the woods & maybe even more so. They don't like seeing their comrades falling dead. When the squirrels around my house see me or the dog they usually haul ass like their tail was on fire or hide for hours and sometimes even all day. Like you, I will often spot 1-2, usually at a distance of 50-125 yards but on occasion they will infiltrate close to the house. That's usually a fatal mistake on their part

. I strive to make GOOD squirrels out of those.
Because I was pushing the shots to longer distances I got a few high fpe air riffles more capable of accommodating the longer shots and switched scopes for ones that I could turret dial. My goal is to keep them pushed back. It will never end

. The key is not to let up. Keep continual hunting pressure on them. In the absence of this said pressure it takes very little time for you to get back to the point where you started.
On a side note, for a variety of reasons I believe there are more squirrels in municipal areas per acre than in the woods. They usually have no hunting
, very limited predation, and reproduce like proverbial rats LOL.