As I see it, there are 2 huge barriers to me ever doing a trial week while currently employed:
1. If it doesn't work out, I've just burned 1/4 of my vacation time for the year. That's a pretty massive ask for a company to make. I could do a bunch of math with expected values, but I'm sure it would work out to Weebly having to have insanely great compensation (>$300k) for me to do it.
2. Even if it does work out with Weebly, it makes it impossible for me to concurrently solicit and evaluate multiple offers, which I absolutely do when looking for a new position.
How do you overcome those problems which make it very unlikely that 99% of employed developers will do your process?
Of course, it could also be that this is a brilliantly designed strategy for weeding out expensive employees by focusing on the unemployed and unsavvy.
This is the result, intended or not.
The problem is, the good people usually don't need a job. So the more of a gauntlet you make your hiring process, the less likely it is you'll get one of those already-employed, perfectly happen and great employees. You're selecting the people who couldn't get jobs at your competitors (modulo the false-negative rejects).
Didn't end up working out so I was glad it was only part time and I didn't make the jump. If I made the jump directly, I likely wouod have been laid off and unemployed.
A full week is pretty close to insane. It means that application is effectively limited to the currently unemployed (or those who are willing to burn what might be all the vacation they can take for months).
That said, it does make pretty clear that Weebly doesn't give a single shit about employee's lives; so it's kind of Weebly to make clear, right out of the gate that they expect to be the only thing that matters in your life.
Contract-to-hire at least gives you a couple months of fairly sure income.
Do you give them a week off in lieu if they get the job?
Weebly has an unlimited vacation policy, so, it worked out pretty well.
Also, from the Weebly end of things, what if you know a couple days in that the candidate isn't going to work out? Cut them off right then or finish out the week?
So, how does a trial week work for candidates committed to another job? If anything, it seems to self-select for part-time or remote workers that are already in a position with time on their hands. The best I know don't fit into that category: you'd miss them.
So, the question is: "Should employers put this kind of burden on every candidate or try a method which demonstrates skill with less time?" I push for the latter.
Likely, the decision was already made by you being willing to risk the week of vacation and put in the effort to get hired, while they showed a similar regard.
You might be able to get away with 1 or 2 of these things a year... but it's a REALLY good way to burn bridges.