If you put them in a child table, your common duration calculation will only need to be made once.
Say you have 5 parts to the process; Plan, check, build, inspect, finish.
And you have a start date & end date for each of those, and in turn a duration.
If you make a child table you would need 4 fields on the child table;
[Part Type], multiple choice field (Plan, check, build, inspect, finish.)
[Start Date]
[End Date]
[Part Duration] = [End Date]-[Start Date]
Now you would have 5 child records for each part of the project, but the great part here is all your "durations" are in one spot, to if you want to make reports, that compare durations from one part to another, you can.
Overall, your reporting capabilities grow greatly because you have all 'like' data in one field.
