The 1-2 days was the interview. And what people had was the chance to build something they chose, something that they felt mattered. People who feel that's a waste of time probably wouldn't be the right fit for us.
Everyone in California is employed on at "at-will" basis. That means they are on trial before their employer everyday. 10-day trials don't change the situation or derisk it for employers. It's already derisked.
This weekend was free to anyone who attended, in a good space, and we provided free coffee and drinks. My employer FutureAdvisor bore a burden of several thousand dollars. It's up to candidates to make some effort, too.
For example, asking someone to switch from a full-time job to contract-to-hire won't work. If the candidate is unemployed, you can hire them for 1-10 days if you want to "try before you buy".
Would this process be less valuable if you paid the candidates $10-$20/hr each for the time they spent? When a good candidate costs $10k-$20k+?