The militarization of US police operations has been the subject of not an insignificant amount of study.

Thats true, I'd say scrutiny, not study in that there is no systematic data that can be studied. AFAIK, only Maryland will be keeping track of raids and that is something relatively new. Other jusrisdiction will have nothing. Getting information will be nearly impossible, and the police deptarments, cities, etc. have incentives to not share such information.

So, these SWAT teams are used in raids once every 3.5 days or so? That seems like a lot.

SWAT is used nowadays to serve pretty routine warrants. Drug warrants on non-violent offenders: SWAT. Gambling--i.e. poker, betting on football, etc.: SWAT.

Here's a fun one where the armored personnel carrier got away from the SWAT morons. Prior to the tank hitting the car, a mother and her young daughter were in the car. The only arrest....traffic tickets, although they were looking for illegal weapons. Oh and they burned down the house, and chased a puppy into the burning house to die.

From the initial story,

And in the ultimate display of cruelty, a SWAT team member drove a dog trying to flee the home back into the inferno, where it met an agonizing death.

Deputies then reportedly laughed as the dog's owners came unglued as it perished in the blaze.

So, stupid, macho, cruel and depraved SWAT team members.

And of course, all of the above is quite within police department policies and guidelines. It is always within guidelines and policies.

So, these SWAT teams are used in raids once every 3.5 days or so? That seems like a lot.

Parts of Maryland are ruff.