After guiding Watford away from the npower Championship relegation zone he was head-hunted by the Royals but just five months into the season he left in December 2009 after a run of disappointing results.
"I probably became more clinical after that," he said. "I went in there looking to change things too quickly.
"I went in thinking 'Right, the club want a new vision, a new philosophy' and I felt if I stripped it down quickly and let it build then that would be okay.
"But what I realised after that was you are still in the business of winning. You talk about football, creativity and invention, but you have to win games - as simple as that.
"That was something very important to me on reflection when I came away from Reading.
"When I went in to Swansea I knew very well I could still work with the same philosophy and identity but I would have to get to the end point quicker.
"That allowed me to round off everything I do and how I work with players and it brought me success at Swansea. That six months at Reading over the course of a nearly 20-year period coaching and managing has been great learning for me.
"Hopefully that will be the defining moment of my career."