You must first understand that there are 2 different cleaning methods, the Dry Method and the Wet Method. There is also Chamber Swabbing which is a wet preventative measure.
The wet method will work 100% of the time but is only required about 90-95% of the time. One analogy is the cleaning of your kitchen floor. You can wet mop (wet method) your kitchen floor every time it needs cleaned, but most of the time you can sweep your kitchen floor with a broom (dry method) to get it clean. When your floor gets dirty with items that are stuck to the floor, you will be required to wet mop it (wet method) to get it clean. Just like when you wet mop your floor, you need to sweep it first to get the big stuff up, you need to use a blower on your sensor to remove the big stuff before using the wet method.
You don’t wet mop your floor every time it is dirty, because it is a more in-depth time consuming process that has consumables. The dry method of cleaning your sensor is faster and is less expensive (usually no consumables) which is why it is the preferred method when applicable.
One note of CAUTION about using the Dry Method, you need to be prepared to do the Wet Method ANY time you attempt the Dry Method. It is possible to make a bigger mess of your sensor with the Dry Method (except the hand blower) if you end up creating a smear on the sensor due to your Dry Cleaning Method device getting contaminated by some stray lubricants or goo.
The dry method consists of using tools like blowers, brushes, SpecGrabbers, lens pens and built in sensor cleaners. The dry method will NOT work on all types of dust; it will not remove dust that is held on by moisture or pollen. There are multiple advantages to the dry method over the wet method with the 2 biggest being less expensive (usally no consumables) and faster.
The wet method consists of putting a liquid onto an applicator and swabbing the sensor. This method is more involved but will remove all types of dust. This is the method that the manufacturers use to clean sensors.
This is not a sensor cleaning function but a preventative measure. You place a cleaner like Eclipse™ on a Foam swab and wipe down the walls of the mirror cage/chamber.