No equipment - Abs exercise. Does combining the muscle groups work rather than doing each part individually?

[step826]

Please refer to this for context: https://darebee.com/ab-exercises.html
As someone who wants to work out their abs could I technically work down the "complete" and "core" columns (the last 2 columns) rather than doing "upper", "lower" and "oblique" separately. Is it better to focus on one muscle group at a time or can combining muscle groups within the abdominal region be a more efficient way for someone who needs to improve in all areas?

 

[Fremen]

Keep in mind that every time you do an ab exercise, you are working all of your abs, not just the part that works the most with that specific exercise.
If you are just starting out, it might be best to focus on full-body exercises with the addition of planks.
As you progress it gets easier to do high reps of exercises so it works better to save time by using planks to tire the muscles and then train them with exercises.
It's just my opinion

 

[Flash_Fire]

I agree with the first part of what @Fremen said, but disagree on making planks a priority and tireing the muscles before getting 'to the meat of it' so to speak.

first of all, many full body exercises already use your abs, but if you want to specifically improve their strength, then they are trained like any other muscle. After warming up you start with the hardest exercise, when your abs still perform the best. That is where you make the best strength and size gains. Afterwards you may go to a lighter exercise (or variation) and do another set (or more).

Static holds (like a plank) are worse for muscle stimulus than when you actually move under tension. That is true for any muscle. You don't hold your squats mid height if you want to build your legs, you move up and down. Static holds and (overcoming) isometrics are only in case there is a specific point in your range of motion you want to improve. And even then, you ought to move around that point.
Just because something is tireing doesn't mean it's great stimulus. There is a very strong correlation but it is not exactely causation.

Hope that sets you on the right path. If you have trouble choosing exercises and want to make sure you hit every part well, then picking at least one that moves up an down and one that has a rotational component will do the trick.