Reading through this tread makes me realize that, to an outside observer, my system looks completely convoluted. But it works for me:
I keep separate systems, one for my "day job" and one for everything else. Anything directly related to day job is on the work system, if I think of something off hours I just shoot an email to my work address and process it the next time I'm in the office. (Reverse the direction if I think of something personal while at work.) Where it gets convoluted is I keep career development and my hobbyist "work" on my personal/home list.
I don't want to be distracted with personal stuff while at work and I certainly don't want to be reminded of the office over the weekend.
Another reason to keep work separate
Although I am a firm believer that the system must include both work and personal and, specifically, you must have a calendar that has both (how will you know when to schedule your dentist appointment if you don't know when that board meeting is?), I agree that there may be benefits to keeping separate work lists (project and next action lists, at least). In the event you cannot be at work, having a complete list of all your open projects and planned next actions can make your substitute's life so much easier. Or if you are sick for five days, can help you get back on your feet when you get back.
And as also been mentioned on this forum several times, if you are discussing your job responsibilities and commitments with your supervisor it can help to have the lists handy.
I would not be as comfortable handing over a list with all my personal projects and actions to someone at work.