Ok, well you won't develop a physical addiction to temazepam or short acting benzos if you use it once a week since the half life is relatively short. Within 30-35 hours the body will have completely eliminated the substance.
In terms of tolerance using it every single week will raise your tolerance over a couple of months if you're using it for recreational purposes.
The biggest problem however if you like Temazepam and benzos in general is that you will most likely develop a psychological addiction. You will start to count the days until you can get high on it again and thats another negative thing, in addition if you'll experience a rough period in your life that " only once a week" will not last and then you'll find yourself using temazepam pretty much everyday. The biggest cause of concern is when you start making excuses to yourself like "this week i'll just use it twice" from then onwards its easy to fall into addiction.
My general rule is that I use them 1-2 MAX. per month for recreational purposes with 4 months "clean" divided throughout the year.
If you stick to this schedule you won't have any problems in terms of tolerance rising and you won't be psychologically addicted to it since it gives enough time for your brain to not think about getting high every weekend.
Hope this helps