I think another reason it lasted so long is that the inconsistency doesn't matter until you reach a certain level of centralization, are trying to do large proj

I think another reason it lasted so long is that the inconsistency doesn't matter until you reach a certain level of centralization, are trying to do large projects and measurements and require a given level of precision. Before that you just measure everything for a particular project using a particular measurement conversion and then when the project is done you're done. Also in a more command driven economy precise planning and estimation doesn't matter as much because it doesn't matter if you underestimated the length of the road by 6% because of inconsistent conversions there was more waste in the system than that and people will work on it till it's done anyways. Another reason is probably the difficulty in actually getting accurate enough measurements in the first place. When you're measurements come from a group of people walking across a plan measuring paces or carrying a metal chain there's enough slop in any measurement and if you're measuring large areas of land you'll be using furlong so you'll convert to furlong-miles. If everyone is doing that the inconsistency doesn't pop up.