that is not good fred, you're saying that an engine will have no power when the turntable is not aligned to a track. which means you will have a constant Ligh on, light off, light on as the track rotates around. this is not good for not just the light, but also the fine electronic DCC circuit board, which as soon as it get's power goes through a start up procedure, get's interupted then has to start all over again. If thsi is a sound board, you may short your DCC system out, as it really draws alot of power on start up.
It is far better to have constant power the Turntable track and to use a reversing module to reverse the polarity as the Table roatabes. This allows the Loco to continueto have it's lights on as it rotates, as well as preserves the integrity of the Electronics.
Your system may work for you, if you don't mind reducing the life expectancy of your DCC boards or shorting the Boosters out or don't mind the flickering ligyts of the loco, but other prefer a stronger, safer better working method.