Hi, many of the extreme twisting and weighted exercises are more advance and should be done only after a good base of training.
Abs are a big muscle group and can be trained almost daily, but you should be aware of other training you are doing so that you are not overdoing.
If you want abs for soccer and strong core then doing higher numbers of reps is the best solution.
If you can not see your abs due to stomach fat you should look at your diet. You can do abs all day but if you have a high % of body fat you will never see them.
Once you can see your abs and if you want them to stand out , then use weighted exercises lower reps to add bulk to the ab muscles.
Don't forget to work on the lower and middle back as well. Doing crunches and situps puts lots so pressure on the back and there are a large percentage of people hurt from overdoing abs.