tiktak292,
If we were working on drafting boards, this may be a meaningful question. I believe all of us are designing on CAD, mostly[ ]3D.
We have to decide how to transition from the CAD[ ]model to the dimensioned drawing. On parametric 3D, features on one part are used to drive features on the adjacent part. I like to set everything to nominal dimensions, e.g. If a 40mm shaft goes into a 40mm hole, I model both pieces at 40mm. If I have a minimum clearance, notice how we must wind up with a +/+ or a -/- tolerance somewhere.
On diameter dimensions, I reset the dimension to limit style tolerances. This is largely because people are rattled by +/+ and -/- tolerances.
Increasingly, people are using Model Based Definition (MBD). This makes the relationship between the nominal model size and the as-displayed dimensions, nasty and critical. The limit dimensions, noted above, actually conceal information. If I show a shaft at 40-0.05/-0.15mm, I am showing the as-modelled size, as well as my required tolerance.
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JHG