I'm doing the NCERT ancient chapters and I'm unsure how deep to go on Sangam literature / Tamilakam beyond what's in the textbook. I don't want to ignore it, and I also don't want to start a separate Tamil history book for prelims.

What depth has been enough for you, based on recent-ish PYQ trends rather than a random telegram list?

I stayed with the NCERT level plus a short note on the main texts and the three kingdoms as the book gives them, and I check any PYQ that went beyond that. I wouldn't start a whole extra book unless your optional is history and you need it anyway.

That's what I hoped to hear. I'll stick to NCERT + PYQs.