If the discharge circuit is not present/functional, it can be months[1], even if the capacitor was discharged at one point.
When working with high voltage/power equipment, its best practice to keep the capacitors shorted while you are working to keep dielectric absorption from “recharging” the capacitor to 1-15% of its rated voltage.
When working with high voltage/power equipment, its best practice to keep the capacitors shorted while you are working to keep dielectric absorption from “recharging” the capacitor to 1-15% of its rated voltage.
[1]: https://academic-accelerator.com/encyclopedia/dielectric-abs...