From a priest:
For those that follow the 1962 calendar or simply follow the traditional penitential days, are the ember days in the octave of Pentecost days of fast? It would seem not since the octave days, similar to Easter, are first class feasts. Your insight would be most helpful.
Good question, Father.
A rule of thumb for anyone, lay or cleric, who desires to follow the “old ways” is: We are bound by the law as it is now, not as it was. If you desire to do a little more, fine! You are not obliged to so by the law.
You will see on some wall calendars for the older, traditional Roman use, little fish icons (which indicate days of fast, or abstinence and of penance) on those very Ember Days.
For example, on a nice calendar sent to me by Canons at St. John Cantius in Chicago, I see a little fishy sign on Ember Wednesday and Saturday during the Octave of Pentecost, a full fish on Friday. So, in accordance with the principles of the older calendar, yes, those would be days of either fast and partial or full abstinence.
Ember Fridays were once, in the Roman Church’s universal calendar, days of fasting and abstinence. Ember Wednesdays and Saturdays were once days of fast and partial abstinence (meat permitted only at the main meal). These days on some calendars get the half-fish icon.
The older, traditional calendar is not at this time the Latin Church’s universal calendar. In the new calendar there are no Ember Days (though diocesan bishops can even now, I believe, establish something like them, and they are vaguely mentioned in the explanation of the present calendar).
It is praiseworthy to stick to the formerly obligatory penitential practices. Penance is good for us and can edify others.
So, (unless you are a professed member of some traditionalist order or institute recognized by a bishop or the Holy See – therefore bound to follow their rules) you can do as you please in this regard.
If you are sticking closely to the older calendar and celebrate mainly or exclusively the older, traditional form of the Roman Rite, then it is logical that you would want to follow the internal logic, indeed wisdom, of our forebears, who had arguably sounder insights into the human condition than those of the perhaps overly optimistic reformers in the 60’s.
If, Father, you are adhering closely to the older form of Mass and these practices, and by that I suppose I mean daily use of the older missal for Mass, then I recommend also daily recitation of the Roman Breviary, which is consonant with the Roman Missal. They complete each other. But ask yourself honestly what you are understanding of the Latin.