If purgatory is a state of being and not a place, how would that affect the purpose of indulgences?
Another related question is if the process of purgation is not a matter of time, how does that affect indulgences?
Purgatory is essentially about a transformation / conforming of the person to Gods will. Purging/Resolving remnant inclinations to sin and temporal consequences of previously forgiven sins.
The acts that merit Indulgences are part of this conforming/tranformation.
without the correct disposition (act of faith through grace) these acts won't merit anything.
The indulgence is a recognition of that journey of dealing with these remnant inclinations /consequences.
Below are some extracts of other websites that discuss the above queries about time / duration previously associated with indulgences / purgatory.
"...The Church revised the norms for indulgences after the Second Vatican Council. Formerly, a partial indulgence was expressed to be an indulgence of a certain number of days or years. It was a popular misconception that these referred to the amount of time one's stay in Purgatory would be reduced. However, they instead referred to the public penances performed in the early Church. In the early Church, a person would have to perform a certain public penance for a certain number of days, weeks or months depending on the gravity of the sin. A partial indulgence was meant to equate to the merits of the public penances of that duration...."
Essentially duration of time was a representative scale of equivalence to early church penances to help give some perspective to the particular indulgence.
In other words the duration was symbolic and was not actually meant to represent time spent in purgatory
From Another website
"...
Myth 5: An indulgence will shorten your time in purgatory by a fixed number of days.
The number of days which used to be attached to indulgences were references to the period of penance one might undergo during life on earth. The Catholic Church does not claim to know anything about how long or short purgatory is in general, much less in a specific person’s case....."