You can never allocate how many minutes a player will get. Strictly follow the depth chart means that the coach will only pick players from the depth chart to play in those particular positions, whereas the coach decides option allows the coach to choose whoever he wants from the team to play wherever he wants, he generally chooses the best player to play in each position.
To be honest probably the best option is coach picks from depth chart in my opinion as this allows you to roughly get the minutes you want as your starter generally gets 36 min and the backup gets 12 or roughly that.
hope that clarifies it a bit