Lately, I have been working on doing Rollouts with the Ab Wheel for several minutes a day. I don't pick numbers or go for some kind of record, hell I wouldn't even attempt to try anything even half of what Bob Backlund has done. The way that has worked for me is set a time and do as many quality reps as possible within that time frame. I don't count the reps or go crazy fast, I just breathe and go.
This is a pretty damn good thing cause it gives me opportunities to challenge my core without killing myself or make the muscles ache like I just had a bad burrito from Taco Bell. It keeps my strength up and is a quick micro workout. It's really only 1 of maybe 2-3 methods of core training I do. The quality of the reps is far more important than numbers cause if you're going so far, how many will you do before it even remotely becomes failure?
It's more than just a core workout, I utilize enough tension (which I'll get to in a second) to hit the arms, shoulders and back to where every single rep is completely controlled and focused. In the realm of tension, I focus on the muscles needed to make the reps work and not just flex and go, I grip the handles hard enough as well so it becomes an Isometric Exercise in the process from that POV. Not looking to build six pack abs or have such a tiny waist, Anna Kendrick can wrap her hands around but to condition and toughen the muscles to where they can take a hit.
When you flip the switch and stop counting reps, you may find you can do more than you thought as opposed to just be fixated on a certain number. If you have a goal in mind, go for it, find that sweet spot with a number or hit a solid rep/set scheme but if you hit a certain number that you normally can do and don't feel much, you're still getting after it but you're hitting a wall on progress at the same time. If you're so inclined, try the method of setting a timer and do reps, start with a minute and see what you do. The idea isn't to go to failure but to hit enough to where you're feeling it but can still go for reps that mean something beyond just repping it and making Speedy Gonzales slow. Be in control of the movement.
The older I get, the more I'm learning to understand that quality over quantity becomes a necessity. Sure doing 100's of reps of whatever has it's perks and you're in great shape, however; if you can't control or stay within range of the balance and strength needed after a while, where does the number of reps really end with? Don't get me wrong, doing 100's of Step Ups and/or Squats is awesome to do but there comes a time where you learn to pay attention (not always on form per se) to how you move. Nobody is going to have the most perfect form (unless you're an elite gymnast) because not everybody will move the same exact way as the next person. The idea is to train so you can minimize injuries, the ego stuff has its moments but overshadowing it can ruin your chances of being able to do things in the long run.
Focus on strengthening the body that will make it easier to get out of bed in the morning, to bend down to pick things up, play with the kids, have endurance for both the bedroom and able to do tasks like in Manual Labor or going up a flight of stairs without getting winded. Make the session count, don't rush it, half ass it or work yourself into the ground. Keep being amazingly awesome.