Change of altitude was propitious for many a WW2 flyer (esp recon as a singleton, or so I am told) but when within the "Stream" at night I doubt that anyone would really believe they had the spatial freedom to do it. The Norden or RAF SABS bombsights (617, 9 (?) sqn) swere working at their limits as it was, so I doubt that other than individual action, that height change was done often. However, I would love to be proved wrong.
Conan