Some people swear on "Final Version" as time management:
http://archive.constantcontact.com/fs004/1100358239599/archi...
The gist of FV is that it takes "psychological inertia" into account to a certain degree - something, that many other systems lack.
To be honest, I never tried it and I don't use any time management system, but maybe it's worth a try for people who don't like GTD.