Hi Mats,
I think I understand why this makes little sens as a 200% assignment would mean working two hours into one. It makes sens though in the following two use cases
Let's say we consider all our resources to be 100% efficient in normal working conditions, and we consider the effort as being done in those same conditions. That is, being constently interrupted, phone always ringing, people errupting in the office, tons of forum posts, you know, the usual So for a task with an estimated effort of 10 hours, we expect any resource to accomplish it in 10 hours. But then, for a given task and a given employee, those conditions are exceptionally optimal for : no interruptions whatsoever are possible. We need to assign this employee like 110% units, so this reflects the efficiency. If that task has two assignments including this one, the other assignment is in normal working conditions so we set it to 100% units.
Another use case is to consider a resource as actually being a team of multiple real people. Let's assume we have 10 teams of varying number of members, but they're all working the same hours. So we have a resource, let's say "The Team", that we assign to various tasks with units corresponding to the number of people in that team. So for task with an effort of 10 hours, we assign "The Team" with 1000% units because there are 10 people in the team, so we expect the task to be done after 1 hour. That's a bit far fetched though and feels more like a workaround but that's what we actually did in our previous software so we didn't have to manually add every single people of a team to every task, a level of detail we don't actually need.
So we use the effort with man-hours units in mind (which I think is correct)) and the resource units as an efficiency estimate. The latter might be wrong and maybe we need to review that practice. Your input is welcome.