The boss recalled the fact that at many times last season the team were leading at half-time and very much in the ascendancy, but failed to build on the advantage after the break and often allowed teams back into the game to claim a point.
He is determined that the sequence will not be repeated in the forthcoming season and challenged the players at Selhurst Park, who responded with a further three goals in the second half.
"I said at half-time that last season we found ourselves in that position quite a lot - 1-0 up, didn't kill the team off and they came back and got a draw.
"So I said to use this as an experiment and see if we could punish them. We did that and took it up a couple of gears.
"I was pleased with the way we played, both in defence and attack.
"This is our sixth game pre-season wise and the first games are always going to be about fitness, I wasn't too worried about results or the way we were playing.
"We had an unbalanced team out in many ways in the first five games and it was about getting their fitness right. Now we are starting to kick up a bit, talking about the shape a bit more and getting more serious about it in a tactical way - how we can pass and keep the ball.
"But this was only another pre-season game and it doesn't mean anything. It was a good workout for us.
"There was some terrific goals, fans like to see some good football with goals at the end of it."
Glenn decided to use being a goal up at the break against Crystal Palace as a test to see if the team could polish off the opposition.