Pre-practice is something I first observed at a Bob Knight practice at Indiana back in the early 80's. It instantly struck me as quality, individual teaching time. I was even more impressed to find out that it was done on a daily basis each practice of the season -- all the way to the completion of the year. It has since been a staple in programs I've been associated with.
Simply stated, it is a period of time before practice where you work on parts of the game that can sometimes be overlooked once the season begins and you are preparing for an opponent. The majority of the time we break our team up into post and perimeter players and work on specific areas in relation to their positions. I've been on staffs that have broke the group up into 3's when space permitted. At times, we will have half perimeter and post on each end when we want to work on areas that incorporate them both.
While we want focus and concentration in these areas, often it is a time where the coach might do a little more talking to explain and correct. We can continue to work on fundamentals such as ball handling, passing, screening, dribbling and defense. We can also work on a phase of the game that maybe we feel the need to improve upon from the previous game. Possibly we did not do a good job of feeding the post so we can break it down in our pre-practice portion. It could also be that we can focus on something of importance for an upcoming game. If we are playing a team that drives the ball baseline from the wing well, we can look at are positioning and talk about and work on that fundamental.
Almost always there will be a drill or two that will relate to our Emphasis of the Day. If our emphasis of the day is screening, as shown in the practice plan below, then we will have a few screening drills in our pre-practice session. In the practice plan below you see "1/0 DS w/2nd Cut" -- which is a 1 vs. 0 Down Screen situation.
I also like the opportunity to communicate with the players during this period. We will spend a little more time explaining while also allowing the players to ask questions they may have.
While staff size can be a factor, I would have a Pre-Practice period even if I was the only coach. Monday I would have the perimeter players come in early with Tuesday being for the post players, etc.
The length of time varies...generally pre-practice last between 15-30 minutes. When we get into the meat of the season, especially in February, we will cut back on practice time but still have a pre-practice period. Again, it makes sure that we never veer to far away from fundamentals and teaching.