I think that common sense draws the line for impractical, and then we move it based on our execution. Right off the bat, obscure setups that have absurd prerequisites (eg glyph exactly this point in the screen, Hsien’s item has to be a star) are impractical. Then we move into unnecessarily difficult combos where a shorter one would suffice. Now, in this case, I mean that if when you compare two similar combos, one hard and one easy, the hard one is only worth using if it comes with benefits over the easy one.
What it takes to deem it practical vary from person to person. For me, if it does a sizable amount more damage than the original combo, or gains a sizable amount of additional meter, then it may be worth it. It all depends on how hard it is. Take Strange for example. The benefits of learning the Impact Palm loop were huge, so I did. It’s practical, because it has huge benefits for a not-too-hard combo. Learning the opener with grounded Impact Palm canceled into glyphs? Worth it. Although it may only work against grounded, it does over 800k solo and mashed, which, if memory serves me right, is about 150k more than just a traditional Impact Palm loop.
But what about those corner Eye of Agamotto loops? That’s where I draw the line. In my team, it would require me using Haggar in the middle of a combo (read: costs 100k and I’ll probably DHC before it can regenerate), and then hitting a tight link, just to get about an additional 30k. Not by any means worth it to me. Little added meter, little added damage, 2 or 3 frame link. That’s what I deem to be impractical.
I tend to think a lot more stuff is practical in this game than most people think. Maybe it’s because I come from SSF4, where people are hitting one-frame links in tournaments. There, your execution is actually considered somewhat bad if you can’t hit a one-framer semi-consistently. I watch people like Latif pulling off the hardest of Viper combos in major tournaments without ever dropping them. Then I come to UMvC3 and people are whining about Lightning Loop. It’s not only practical, but essential to a good Zero. I don’t know, I just think you guys are underestimating yourselves and the community as a whole.