Filtering Capacitors Around Flyback Transformers In CRT Monitors

[Hitto]

I have a question about the filtering capacitors to be used around the flyback transformer in CRT Monitors.

I mean the 10-22-33uF capacitors which filter ~160V voltages going to the flyback trafo.

1) Do they have to be low E.S.R.?
The original capacitors are usually general purpose, but I suspect this was for cost cutting more than a requirement.

2) Is geometry and picture stability improved in case of increased capacitance?
I've seen schematics on similar models of some old Sony monitors: identical flyback transformer but capacity increased from 33uF to 47uF in a more costy version.