So why can't your dashboard show different metrics each day? You can just configure the different widgets to show up at different frequencies.
Perhaps your 401k widget only shows up the first time you log in each quarter. Your weight tracking widget only shows up Monday morning. Your banking and monthly budgeting widget shows up daily. Your Amazon order shipping widget shows up only when you have an open order. Your meal plan widget shows up all the time.
You can choose which widgets you want. If you're poor and don't have a 401k, don't turn on the 401k widget. If you're rich and skinny and don't have problems maintaining either of those, don't turn on the budgeting and weight loss widgets. But a shared dashboard doesn't imply everything on the same frequency.
I already have a page where significant announcements show up at a wide variety of frequencies. It's called "webmail". Or an activity feed.
The point of a dashboard is that no navigation is required beyond turning your head and glancing. Dashboards are for things that you want to see by accident, or while waiting for a phone call. A widget that usually isn't there when you turn your head might as well not be on the dashboard at all. If you have to click to see it, it can be in a separate app or site. If you have to wait for a specific date and time to see it, it might just as well arrive in your mail, Twitter stream, or SMS.
The main difference in my eyes is that activity feeds and messages can create a backlog. The user experience isn't quite right either--different types of messages still look exactly the same. But different dashboard widgets could have radically different user experiences.
Perhaps your 401k widget only shows up the first time you log in each quarter. Your weight tracking widget only shows up Monday morning. Your banking and monthly budgeting widget shows up daily. Your Amazon order shipping widget shows up only when you have an open order. Your meal plan widget shows up all the time.
You can choose which widgets you want. If you're poor and don't have a 401k, don't turn on the 401k widget. If you're rich and skinny and don't have problems maintaining either of those, don't turn on the budgeting and weight loss widgets. But a shared dashboard doesn't imply everything on the same frequency.