“When a Post-feast falls on a Sunday, in Saturday Vespers
At Lord, I Have Cried, we chant 6 Resurrectional Stichera from the Octoechos and 4 from the Menaion, from the post-festal stichera that are in the Menaion for the calendar date. For example, if Sunday is September 10th, we would chant the Stichera that have the heading ‘Of the feast’. “
I’ve also never seen this. I’ve always seen the festal hymns taken from the feast itself, not from whatever calendar date the Sunday falls on. (For example, today/last night the stichera in vespers and orthros were the festal hymns from Sept. 14th, not Sept. 17th.)
Is this another case where the typikon says one thing, but everyone does something else?
This is a good question. In Violakis in particular, unless it is the day of the feast itself or the Apodosis, for post-festal Sundays, you will chant the hymns of the feast that come from the Menaion on that particular day. The reasoning is that, especially in parishes, these post-festal hymns will never be heard since parishes don’t have daily services. For this reason, Violakis will usually use the Sunday after a feast to feature hymnography that was absent on the principal feast.
However, what Violakis appoints is different than what is found in the TAS, which appoints the hymns from the principal day. This is for sure a significant point of divergence. Both practices are acceptable, but in whatever you decide to do, be consistent.