Best resource for tactics training?

I personally like using Lucas Chess for tactics training.  It has a feature for learning the tactics using the spaced repetition learning theory.  I find I retain the patterns much better using this method.  Chesstempo.com also has a spaced repetition option (it may be for gold members, which I am so I'm not 100% on whether it's available to everyone or just gold), but I like using Lucas Chess locally better.

I think it depends on what part of tactics you want to train.

For pattern recognition, I enjoy chessimo. Chess tactics server is a good alternative.

For calculation and implementation of said patterns, I use chesstempo, but chess.com is an equal alternative if you're a paying member.

More than anything, consistency is key. Just like running 5 miles one day will not reduce your weight, 5 hours of tactics training on one day will not benefit you greatly. You have to run every day to lose weight. Not 5 miles every day of course, but you get my point.

Wow!

well it depends on how hard your trying at the end of the day do those extra puzzles or what ever your using to get good at chess.but if you want to get good at tactics you could buy books from Amazon for 30 bucks and theres alot of puzzles for you to train.also if you want to get better at spotting tactics you need to learn the logic behind it if your putting in the effort and time you will become better.