OP here - just as a continued update from my post.
I still think at 1100-1300 level, my advice was good - repeated study of tactics, particularly, reviewing tactics you INCORRECTLY solved, is crucial.
I will however, amend my prior post where I assumed that by just doing more tactics in that pattern, I'd probably gain 200-300 more points. That clearly was NOT the case. I got a pretty rude awakening at 1350ish level, when players with much better opening and basic positional knowledge (simple stuff, really), gave me few to no chances to strut my tactics stuff.
Unsurprisingly, I think the take home msg that's common sense, but needs to be reiterated, is that balance in study is the highest yield in chess. Tactics should be emphasized first as they're the most decisive, but you have to add the other stuff to play decent chess games pretty soon afterwards. My positional practice knowledge (simple stuff but which I was not executing reliably, like capturing the center, not moving 2 pieces in the opening - stuff that sounds beginner/rookie but I guarantee even 1450s are routinely ignoring since I'm about that level now!) was really lagging my tactics and it showed.
I thought blitz was all tactics at first, but even in blitz, good positional moves are required to set up the tactics, or to give your opponent so few viable moves that it becomes really easy for them to blunder.
Loved this post. More people need to read it. Thanks for sharing.