I can’t tell you why you should have a regular confessor, but I can tell you why I find that it is good for me.
I am an introvert and find it difficult to open up to people. I find that having a confessor who knows me well helps me to make a more thorough confession because I do not have the awkwardness that I generally feel with strangers or acquaintances. I am able t give more pertinent details because I don’t freeze up with anxiety. A regular confessor (or my confessor, at least) probes my conscience a bit. He helps me to go deeper and understand the sins underlying the surface . He tailors the advice he gives me to my circumstances and my personality. He sometimes gives me penances that target my sins in a way that could not happen otherwise. He’s been known to question my purpose of amendment and thereby helps me to strengthen it. Because I am comfortable with him, I ask him questions about my sins, and sins in general, that would otherwise go unasked. It helps with accountability. I go to confession more frequently because I feel comfortable enough to ask for an appointment when I need confession.
