Got my account verified, still don't understand how the limits work

Finally sorted my site verification last week after putting it off for months. Posting because I couldn't find a straight answer anywhere before I started. They asked for CNIC front and back, and a selfie holding it. The bit I still don't understand is the limits. Mine went up after approval but I can't find anywhere that explains what determines the ceiling. Anyone here know how that actually works? Does it go up over time or is there something specific you need to do?