As far as I know there is no gambler who only gambles once a week because it is an addictive drug like cigarettes which is hard to give up. On the other hand you cannot earn certain money from gambling so it is not really ideal in your personal life. According to me rich people can gamble because they have enough money to back up but a common man can be destitute when he gambles. I gamble but when I have more capital it is a secret from the society and I don't always tell the family. I expand the money I earn from gambling into other businesses but always keep my thoughts straight.
Good for you if you can make profits and still be disciplined.
But I tell you, there may be gamblers that really play once a week or just during their off to work, Saturday or Sunday. It can happen especially those who are just betting on sports. Most events happen during Saturday night so there's a chance he is only doing that on that day. It's different with casino players, there may be those who also play on weekends but there are more gamblers who do it every day since gambling sites in this era are easy to access.
In my case, I gamble small and try to pursue the jackpot and when my balance is gone I rest for a long time until I have saved enough money to play again. In that kind of strategy I somehow made some money and a big part of that money is spent for the family so I am happy with it.
On OP's question on how to avoid it, be busy with something else. That will really help a lot if you are always occupied with something and be sure that you love that activity.