I'm new to GTD, having discovered it via TiddlyWiki and the GTD derivatives.
Presumably many on this board have a vested interest in GTD, or find that it works for them. Are there any other systems which also work?
For a long while I used spreadsheets with the following types of information:
Task, start date, end date, priority, type, hours (minutes) required,
hours required per day and a few other fields.
Each time a task was done it was struck off - not deleted - as this kept a record of everything done. By using a simple time accumulation formula, it was possible to estimate the total time required for all the tasks in the given priority order. This enabled me to decide how many tasks could be dealt with each day, by re-ordering the priorities. It also enabled me to decide on the overall feasibility of getting things done on a daily basis.
It seems to me that simple GTD does not quite do this.