Well I regularly do indeed wing it in Blender. It is poorly suited for conforming to specific measurements out of the box, but with some plugins it's usable enough. Definitely wouldn't imagine it being in spec for any professional usage but for hobbyist maker stuff getting within 100 microns is more than accurate enough. I mean hell, I can't really measure much more accurately with my callipers anyway.
Honestly from the way you are describing your workflow, it sounds like you haven’t actually dipped into parametric design and you’re still creating your models very manually.
Let’s say you have a hole in a part and you need it to be a certain distance from an edge.
The rookie way is to pull out your calipers and actually measure that distance and put it into the design.
But let’s say you know the hole needs to be co-tangent to an invisible line between two other points. In a parametric modeling program, you would say it as it is: this hole is co-tangent to this invisible line which is defined by these two points.
…which gives you a HUGE advantage: let’s say you have to move one of the defining points… well because you defined it parametrically, the hole would just magically resize and reorient itself instantly. And let’s say you extended the hole parametrically to another surface… well that would update too.
But if you did it the rookie way, you would have to pull out your calipers and re-measure everything. Risky risky too. Have to double check all your measurements all over again.
In Blender, because shapes are not actually mathematical shapes, you aren’t going to be able to define co-tangents or constraints or derive any measurements.
That’s why, no matter whether you are a hobbyist or a large professional engineering firm, you might much prefer parametric design because it saves you so much time when drawing out or changing the part. It has nothing to do with the precision of your calipers or the precision of your final product.
(That said, not all tasks are fit for parametric design. I wouldn’t design a game model or rendered scene with parametric design. I would use Blender. Also to be said, I know there have been attempts to add parametric design to Blender but I’m not familiar with how far they are.)
