Cache invalidation is taking time - affecting product management and marketing

[Pinakee BIswas]

Hi,

We are using PURGE or varnishadm ban to invalidate the cache but it's 
taking time for the same. Morever, it is not clear how long it takes. It 
is not clear which method is better and smoother - PURGE or ban.

Is there a way to control the timing of cache clearing as it's affecting 
our product management and marketing?

Thanks,

Pinakee