How do you test blades?

I think the only way to test is to use a blade for a while, a month maybe, and then switch. I'm not sure I'd be able to pick out comparisons after one use. But I am a comparative novice. Sadly I would describe my skin as ultra sensitive, but since using the shavette (never used a safety) there's not been any issue apart from one pre shave lotion. I am a strict with-the-grain shaver and the only place that needs two passes is my chin. A feather blade in a shavette pretty much does for me now. It would take a lot for me to consider switching.

I also never ever re-use a blade. Once I'm finished it goes in the sharp bin.
 
I would argue, and this will be my last input here as people have probably had enough of this broken record, that when used properly a milder razor will need no extra passes to get you to BBS. If the blade is on your face it will shave at face level.
 

You are confusing aggression and efficiency. Most quality mild razors are extremely efficient, such as early Techs, all Super Speeds, Star DE's, and many more.
 

Most blades don't smooth out until the third shave or so, including Feathers. If you only use them once, you never experience the best shaves a blade has to offer.
 
It's pretty simple really. I find personally that I get the best result with a fresh blade. So that's what I do. I'm also not keen on reintroducing all the staph back from a pre-used razor. High staph is the reason I started shaving in the first place.
 
I use new blades for the first time in my Feather AS-D2. IF they work in that razor they should work in any razor! Then comfort in shaving with any razor is my next guide line. Razor blades are all razor sharp. But, some work the best for each person's face in the razor they like to use best. Like buying shoes or any other personal item?