I would say traders fails to meet up with discipline and skills in trading. The amount of knowledge one has towards trading will determine what will be the outcome in trading. The reason why traders normally jave challenge with their outcome in trading is because is because they feel the amount of knowledge they have concerning trading is enough to make trading successful.
Trading strategies do change overtime and one don't need to rely in a trading strategy, it is important for a trader to acquire skills that can enable him to be successful in trading. When it comes to discipline it is something most people find it very difficult to practice, knowing that trading is about discipline to obtain a successful trade.
It is a problem that often occurs even with those who have good knowledge sometimes can not control themselves by forgetting the discipline that they previously had to obey. In addition, with now where the development of technology is increasingly sophisticated, it makes it easy for us to find any information, with this we should be able to use it to find broader knowledge about trading which aims to prevent losses.
With those who trade but do not have enough knowledge in my opinion are people who are lazy to process but only want to enjoy the results.
With strategy I think everyone has their own strategy and they will continue to develop their strategy, for example the strategy they have is less accurate, the possibility that will be done is to find a new strategy that is more efficient but with those who evaluate strategies or do research it is very rare. And sometimes I see some people who have teachers in learning trading only this is not free, and this person is in my environment with luck he succeeded in trading.