Iran has only had working P-1 centrifuges for enrichment. Crude but eventually effective.
Iran’s problem is that their fuel is heavily contaminated with molybdenum. Moly atoms are almost the same “size” as uranium and plug up the centrifuge tubes, destroying them.
So what Iran has been doing all this time is refining out the Moly to get pure uranium fuel that can be quickly enriched to weapons grade, 85%+.
So the weight of the enriched fuel stays close to the limits, but it is much purer as time goes on.
If they can ever get a P-2 working, they could produce enough for a small atomic bomb at least every 30 days from a device the size of a refrigerator drawing very little power, virtually undetectable.
How many centrifuges does North Korea have?