Many places have a 30 day return period. Check out Music Direct. You have 30 days to decide if you like something or not.
And I would have say you are truly gifted to be able to decide in 30 minutes. I think you have a lot to learn.
On point 1, that's kind of a douchey thing to do. When you send it back, they can't sell it as a new item, it has to be an open box. You're essentially costing the company money so you can just play around. It's nice to have, but to do it with several dozen headphones is really not cool.
For point 2, I think if you can't figure out what a headphone has going on after a half hour then your ears are broken. You might not be able to say "well there's some grain in the 5KHz range and I hear a tiny hump between 80Hz and 120" but if after a half hour you're unable to get a feel for the shape and style of a headphone's sound maybe the issue is on your end.
What you MIGHT be referring to is a person's decision process, which for some people is instant and for some people takes forever. Of the various headphones I've owned over the last year or so, ranging from the DT770 to the LCD-2.2, within a half hour I'd know if I like it or not, but external factors can change it over time. Even the headphones I've sold aren't because my opinion of them changed, but rather because I started to want something different.
I hear this a lot, the whole "it takes weeks of auditioning," and it bugs me just as much now as it did then. It essentially leaves everyone in a perpetual state of indecision because they're always going to think that what they have isn't as good as what they could have because there is simply no way to listen to all the possible headphones out there.
For that matter, when you say "two weeks", how many hours is that? One hour a day? Two hours a day? How much of a given headphone is necessary? What if you have a dozen headphones to decide between? Are you talking several hundred hours of listening before you can decide which to keep? You're talking months and months of hardcore auditioning. That's just absurd.