My complex conversion was done by an Ex-BA pilot who had flown most aircraft from King Airs up to Concorde.
He was adamant that I did not step on the brakes during the retraction process, for the following reasons;
a. I you watch the wheels during the retraction process, they are nearly always stationary before the main gear starts to move and, unless you are fling a fast jet, are always stationary before the u/c moves through 45 degrees.
b. It's an un-necessary distraction during a process with enough distractions
and
c. When you stand on the brakes, it has the effect of making the brake hoses become quite rigid at exactly the time that they will need to be flexible. If you do this once, it's 99.9% certain that no problem. If you do this 100 times, it's unlikely to cause a problem. But if you do this every day for several years, you may cause a problem, either through a premature hose failure or, more likely, a stress fracture of one of the mountings.
I have never touched the brakes upon retraction, and can see no tell-tales on either the tyres or the blocks in the wheel-wells to indicate rotation at the time of retraction, on either my arrow or saratoga.
