This is all stuff I have found worked really well for my clients.
As you progress through your training career there are certain strategies which suit each phase better.
As a beginner, you are best of lifting 3 x week using a whole body split (you hit the whole body each session). This is the easiest time in your career to progress. You should gain strength and muscle quickly. Be sure to eat enough calories to grow (16-20 x BW in pounds) and enough protein (1g per pound). In your first year you should gain 20-25lbs. If you’ve been training for longer than this and haven’t achieved it then, the chances are you are making some key errors.
Once you been training properly for a year you begin to transition towards the intermediate category. This is where most lifters find themselves. Many never get beyond this point. This phase should last around 4 years. During this time you are best served training 4 week and doing most of your training on an upper/lower split. This means you can hit every muscle group 2 x week with moderately high training volumes. At this stage you are bigger and training more so you need more food than you did as a beginner to grow. You should also track things more closely. So rather than just worrying about calories and protein you should also track your carbs and fat intake.
At the advanced level, gains are harder to come by. You need to do more to grow. As a result, shifting to training 6 x week using a split like a push/pull/legs is a good idea. Just like intermediates need more food than beginners, advanced lifters will need more than when they were intermediates. Pay attention to the details and consider things like nutrient timing. Progress at this stage is slower. A few pounds of muscle per year is realistic.