I would need a lot more information. But training each muscle group one time each week is not goint to yeild very good results for any purpose you might be looking to achieve.
I highly recommend contacting a fitness instructor in your area. If you are a fitness instructor, I recommend you review your manuals and do some research on frequency, intensity, duration, and recovery.
I teach CECs for instructors, check out my website at www.hawaiifitnessacademy.com .
To answer that question it would help to know what fitness goals you are trying to achieve.
If your current strength training program is working for you then continue. I would also add a component of cardio to your program a few days a week for added health benefits.
Again, it depends on your specific goals as to whether or not this program is good.
To be honest with you, there is really no correct answer to your question. The reason is simple: it depends on the person, their genetics, their diet, their training regiment/program, their resting/recovery time and more important their mind. For this reason, you need to find out what works best for you and stay on that routine. If the routine you have described is working for you then keep it as is, if not switch to a different one. You could switch the days of one muscle group with another one or add one more group to a particular day or take more days off or even switch your diet. I know this sounds complicated, but only you can find the right recipe that works for you.