I use a sweep second hand clock for timing development when printing. Works perfectly. This is also good for group darkrooms.Seems like I'm the only one here who just uses a plain old clock or watch for timing development / stop / fix.
For those considering the option, look for a battery powered one, with 12 big numbers, and avoid anything with red numbers or hands, particularly the second hand!

yeah. but now you've got me thinking. maybe i need to make a homemade sand hourglass or water clock or something.... hmmm..
(but I will not deny its usefulness!)