I do believe there was some general rule like this and I suppose I could find the details if I had to do so. What I believe happened was that the Church first said that those who could not genuinely satisfy the obligation on Sunday, e.g. doctors, nurses, firemen, police offices, etc., could go to Mass on the previous evening. Then I believe the rule was changed so that everyone no matter what their circumstances could fulfil the Sunday or holy day obligation on the previous evening. I am almost certain, without checking, that the latter came in during the pontificate of St John Paul II. Nowadays, I don’t think I could name a parish that doesn’t have Mass on Saturday evening.
