For any kind of lifters, the key to continued progress is called progressive overload. Basically, you need to do more than you are doing now to force your body to adapt. Volume = weight X reps, so if you increase the number of reps, sets, weight/intensity, or frequency of training, your total volume automatically goes up. You could increase intensity and decrease volume and still make gains, but the focus would be more on neural adaptations rather than hypertrophy. If you want to get bigger and stronger then you need to do both.
There is no "best program", but there are different programs that work for different people. Lifters who use steroids can make more progress than natural lifters with less frequent training because the drugs increase the time of muscle protein synthesis cycles. That's not to say that training each lift once a week definitely can't work for natural lifters, but chances are that you would make better gains training more often. In Norway, a lot of lifters are now training 5-6 days a week because of a study that found increased frequency with the same volume to give better results, but they are also using low volume per session and every set is far from failure.