IST is a pretty long flight.
8-9 rows of CE (which I regularly see nowadays, sometimes I see 11 complete full rows, although I can't remember seeing 12 rows very often personally) does not seem to present the crew with any issues on former Band 4 that's shorter than IST completing the meal service with at least 1 hour to spare (usually a quite a bit more) so I don't think the crew members would struggle with 12 rows on IST at all to be honest.