Houllier is keen to ensure his players stay fresh and sharp by making use of all of the talent at his disposal.
He has been impressed by the attitude of his players to improve during his month in charge ahead of Saturday evening's home clash with champions Chelsea.
Houllier said: "We have a squad of 20 to 25 players so not everyone is involved every week.
"But in football, we know we need everybody and everyone contributes to the final success.
"Some may not be called up for this game or that game but could appear in two weeks' time and be the hero.
"There are injuries, suspensions, lack of form. Sometimes the tactical approach to a specific game is different so you need different players.
"It is not my view to use the same 11 all the time because I think some players can get tired and you don't want to ruin their confidence.
"Sometimes you have to rest them because quite a number of players here are developing their game."
Houllier slowly but surely intends to make Villa into more of a passing side and has been using double training sessions to improve the fitness and technical levels.
He said: "We have a squad of good lads. They show a lot of application and a lot of professionalism.
"They have a good attitude and a liking to work, which is very important.
"They are eager too to learn, improve and progress."