First of all, it is not "known" you "have" to work out your abs every day. You don't have to work them out at all if you don't want to. So obviously you have a goal in mind. There are no experts on these forums, just people who do what you do, hopefully, who can share experiences. But abs are basically part of a core workout, while other muscles might not be. Core exercises are hard, but you usually recover from them more quickly than, say, if you're doing power sets on a bench press. We have no idea what parts of your body you're working or why -- exercise can be for fun, for health, for losing weight, for getting oversized muscles, for performance in a sport -- so your entire workout would go a long way to answering this question. I personally don't think it matters much unless, say, you have a bad lower back, in which case you might want to wait to do abs for last so you can then ease up the stress on the lower back. Or say you eat just before working out -- not a great idea to do abs, where the food is digesting, soon after eating. Everything depends.