Imo if they only been flying half an hour once a day although it was three and half weeks, they still wasnt at the required fitness they should have been at before being basketted. Birds that get let out once a day should fly with vigour, and freely, so i would say you may have an issue with your feeding or the health isnt 100% correct. I would also always make sure their heads are clear of respiratory/ornithoses before id ever train old or young.