I'm on my third beard, but this one is 47 years old. I do shave the upper sides for a clean line and a bit around the neck. I used to use the Bic disposable razors but when Gillette came out with the double blade Excel razor that's what I started using and still do.
I buy my blades in large quantities (cheaper that way) off eBay. You have to be careful though because there are many "non-genuine" blades being sold. I know that's true for the Excel blades and probably other brands as well. You can Google it for more information on how to tell the difference.
Even though I'm only shaving about half my face my blades will last for weeks due to a little trick I discovered a few years ago. Like most of us I run water to keep the blade rinsed after one or two strokes. And for years I've used an old toothbrush to brush the blades under running water when done. But then I read something about the microscopic properties of steel (stainless in our case) and rust. So now after my final rinse of the blade and shaking as much water off as I can I added a couple of good puffs of air real close to the edges of the blades. Ever since I started doing that a couple of years ago I discovered my blades (from the same batch) are lasting twice as long.
BTW, if it makes a difference, I don't use any shaving lotion or gel. Just warm skin, usually from showering, and a blade warmed from hot water.