Even when I could get coins on the web, I didn't as I'm usually browsing ali on the app. Now the daily coin grab from the app is upped to match or pass what you could get from doing both.
I have about 27k in coins, but I really don't even think about it. Its nice to see a small discount at checkout though.
There is the coin page that will feature items with bigger coin discounts, but I don't think I've seen any exceptionally good deals there.
Agree that waiting for the big sales is the way to go.