It's a great tool for junior developers. If someone hasn't had a dev job before, then a personal project -- even something simple like a twitter bot -- is almost a requirement in my eyes. IME, it is a strong signal for capability at that skill level.
Most higher-level devs don't build personal projects. I've worked with plenty of ridiculously capable people who work 9-5 and go home to their family. If anything, diligently keeping set hours is probably a stronger signal for a good senior candidate than personal projects are. A good senior candidate should be doing the thing they want to do already (thus, no need for side projects), or be capable of getting everything they need done for their job in 8 hours or less.
Most higher-level devs don't build personal projects. I've worked with plenty of ridiculously capable people who work 9-5 and go home to their family. If anything, diligently keeping set hours is probably a stronger signal for a good senior candidate than personal projects are. A good senior candidate should be doing the thing they want to do already (thus, no need for side projects), or be capable of getting everything they need done for their job in 8 hours or less.