Received an email to work on a design exercise to optimize not 1, but 2 of their current product interfaces. I've decided to only provide 1 mockup because it didn't really make sense to put so much work in this without at least a prior phone interview. That and I have been screwed over in the past where I've put a ton of hours and energy in these "design exercises" to redesign websites only to never hear anything back. Lo and behold, a month later, they never bothered to email me back. Mind you I have been sending a follow up emails to check in so they have the reminders. While I do understand when companies ask for potential employees to show their skills, it's companies like this that ruin the experience for everyone.