I think it depends on the person. Some do and some don't. I do it whenever I have a major life change.
Do you think its best to inventory yourself often? 3-6-9 months?
I don't think I've ever done that to be truthful.
What does it mean "to inventory yourself "? I have never heard this terminology used before.
No:
I use myself a lot, but never to the point of having to keep spare body parts on hand.
And Yes:
On the other hand, as a being who exists in time, change is a law of my being and I keep constant tabs on what changes.
When I have a birthday that ends with a zero I might look back and wonder where the last 10 years went but I've never "inventoried" myself.
It's a bit like filling in your tax return. You wonder where all the money went. :-/