Trials/Challenges in Fighting Games - Should they be Difficult or Practical?

As you know, many fighting games have some sort of combo trials in them.

Developers make them for every character in the game, and while some of them can be mad easy like doing one unique special move or doing a simple hit-confirm combo, as you progress through the trials, their difficulty starts to increase tremendously, often to the point that those combos are specifically designed for full meter usage or ones that you would never really land in an actual match, either for resource management reasons or heavy scaling, or they are designed for use in a specific scenario (mostly corner-only) which is also not as realistic in actual matches

For example - look at this combo in Trial #8 for K’ in King of Fighters 13

Or at this Level 22-24 trial compilation for Street Fighter V

And there are probably many other examples that you guys might have seen yourself

So considering how the challenge modes are usually made - would you prefer them to be based off the combos that players use at a competitive level (like Sakura tatsu loops or Yun Genei-Jin juggles in SF4), or have them be made specifically to train precision in execution by giving you harder and sometimes next-to-impossible or highly unrealistic trials, or combine both but gradually increase the difficulty so that you would be able to really make the most out of your character by honing the skills of handing him/her as you progress through the challenges?

Maybe you have other ideas for these modes?

Trials should always contain basic newbie friendly combos, useful BnBs (intermediate in difficulty), then intermediate combos (aka more advanced BnBs) and then end with a couple of yolo advanced swag combos.