Lately I have been solving coding challenges. For the sake of solving them only. I submit them, wait for "good job!" or "nice work!" and move on to the next challenge--at the next company. After a few months or years of doing this, I may decide to advance to technical phone screens on shared documents. I'll try that for a while. After that who knows...
I understand the desire for a challenge, but you might consider not submitting them. Effort goes into advancing a candidate's application at each stage, so someone out there is wasting their time so you can get your "good job!" boost.
It's a tough market. It can take years to hone your problem-solving skills. And years after that to hone your technical-phone-screen-on-shared-document skills. This takes deliberate practice. When I'm ready to advance to the next stage, I will.
There is a serious point: companies often aren't forthcoming about day-to-day working conditions. But the response you get to your puzzle solving activities can be telling.
