If you want to plan your work in a very detailed way, or if you need to
produce offers with quotations of the estimated work effort, you may want to
assign effort estimates to entries. If you are also clocking your work, you
may later want to compare the planned effort with the actual working time, a
great way to improve planning estimates. Effort estimates are stored in a
special property ‘Effort’1. Clearly the best way to
work with effort estimates is through column view (see Column view). You
should start by setting up discrete values for effort estimates, and a
COLUMNS format that displays these values together with clock sums (if
you want to clock your time). For a specific buffer you can use
#+PROPERTY: Effort_ALL 0 0:10 0:30 1:00 2:00 3:00 4:00 5:00 6:00 7:00 8:00
#+COLUMNS: %40ITEM(Task) %17Effort(Estimated Effort){:} %CLOCKSUM
or, even better, you can set up these values globally by customizing the
variables org-global-properties and org-columns-default-format.
In particular if you want to use this setup also in the agenda, a global
setup may be advised.
The way to assign estimates to individual items is then to switch to column mode, and to use S-<right> and S-<left> to change the value. The values you enter will immediately be summed up in the hierarchy. In the column next to it, any clocked time will be displayed.
If you switch to column view in the daily/weekly agenda, the effort column
will summarize the estimated work effort for each day2, and you can use this to find space in your schedule. To get
an overview of the entire part of the day that is committed, you can set the
option org-agenda-columns-add-appointments-to-effort-sum. The
appointments on a day that take place over a specified time interval will
then also be added to the load estimate of the day.
Effort estimates can be used in secondary agenda filtering that is triggered with the / key in the agenda (see Agenda commands). If you have these estimates defined consistently, two or three key presses will narrow down the list to stuff that fits into an available time slot.
[1] You may change the property being
used with the variable org-effort-property.
[2] Please note the pitfalls of summing hierarchical data in a flat list (see Agenda column view).