This is EXACTLY what I'm talking about.
The 2 US-Based race schools I've taught for used the larger ones for this reason, because you have actually go around something.
try it with both and you'll find you actually approach things much differently with an object to avoid.
If you're talking M2 skills, the tiny ones are fine.
If you're looking for advanced skills, practice how you want to perform in the real word(avoidance is the key)
because this is practice, you can also build in a buffer zone initially, to ensure you have room to abort, but another skill is to actually test riding into one of them, clipping one with a bar, in a controlled condition to see what happens.
Anything you can add to your skillset as rider has value.