How many hours have you accumulated?
Currently 185+ hours and maybe half of that again in unrated mode.
Has it increased your chess knowledge?
I feel it has helped with certain attacking patterns for sure, but there are also negative sides to working exclusively with the tactics trainer here (as I have mentioned before elsewhere) and now I rarely use it, only for brief warm ups or on the go here and there.
Positives include:
* lots of attacking patterns
* Good stats tracking
* Clear interface.
Negatives include:
* The timer (in V2) is too quick and encourages bad habits, especially for developing players.
* Many of problems are sourced from inferior, low-level games. This means you are often solving positions from poor quality games and unrealistic positions.
* You are awarded points for 'partially correct' i.e. wrong answers, thefore you are credited by making poor, sometimes losing moves.
* There is an unrealistic balance between attacking and defensive problems - maybe 95% attacking, 5% defensive, meaning you are not training in a balanced manner.
* The post-puzzle analysis functions (including comments) are often not helpful and certainly better elsewhere (Chess Tempo).
Was there a certain number of hours, in estimation, that appears to be key for improvement? (similar to studies of excellence).
I'm not sure what 'studies of excellence' is, but I don't think there are any x number of hours that are key to improvement and I think it would be different for different people.
Also I don't think tactics is something that you can train and then suddenly stop doing, rather I think tactics training should be seen as an ongoing process and part of a regular training programme. (Top GMs still train tactics daily so...)
The bottom line for me is that there's nothing wrong with using TT here in moderation, but for overall tactial improvement I would recommend using a range of tactic trainers and good books of varying levels of difficultly and styles.
Restricting your reply to the tactics training here at Chess.com,
How many hours have you accumulated?
Has it increased your chess knowledge?
Was there a certain number of hours, in estimation, that appears to be key for improvement? (similar to studies of excellence).