The ultimate answer is 'whatever is practical' but for me, I use reminders to tell me when I have to be in a meeting in 15 minutes if its at the office or with an appropriate lead time if I have to travel.
For tasks I do not use reminders at all as they are impractical. There are literally hundreds of items in my tasks and through categories, duration and priority I rank them in terms of importance. Tasks range from "do that import for customer x" through to "read that article on CRM". for the vast majority of tasks, there is no deadline and to schedule them is too rigid.
Within reason, at any time I could be called into a presales meeting or conference call so to think that I'm going to jump when Outlook says 'do this' is folly. I have my list of tasks, I work through them.
The great thing about CRM is its flexibility. You can use the notification accelerator to generate a 'queue' within Outlook of any records you like. Rather than use reminders, you could send emails and for those who have no interest, you could set up Outlook rules to filter them out. You could also have 'defcon' levels of reminders and embrace the 'and'. That is, have a reminder that a task needs to be completed and then if the deadline passes another reminder or escalation process. There is nothing worse than 'death my reminder/inbox' though so make sure you don't overwhelm.
Leon Tribe
Want to hear me talk about all things CRM? Check out my blog
http://leontribe.blogspot.com/
or hear me tweet @leontribe
Want to hear me talk about all things CRM? Check out my blog
http://leontribe.blogspot.com/ or hear me tweet @leontribe
