I criticise poor training every week but I only praise training once a month which I do at the beginning of each month. I prefer only to praise for a performance of 8.0 or higher but at the beginning of the season when nobody ,or virtually nobody, is hitting 8.0 I praise for 7.6 and higher. This works fine for me although I occasionally have a youngster tell me that I'm criticising him too often which I interpret as an indication of a poor personality and he's immediately on the unwanted list.