I agree with that. The dog must learn that there are disagreeable consequences when he ignores an easy, well-trained command. So I had to show Rhian that SIT means SIT, even if there is something interesting around.
The other thing is practise. To stay with the example of SIT, I practices this indoors a lot, not only in training sessions, but also in between. Then in the garden or in a boring place, on lead as long as she didn't put her bum down instantly. And of course I rewarded her for quick compliance, sometimes with a huge jackpot!

Then slowly increase distance and distraction, one at a time.
I still do not give the SIT command if Rhian is chasing a cat at full speed - I know she'd ignore it. If I can catch the moment before she takes off, she'll obey. Criteria are different for every dog, for some a moving twig might be a big distraction, for others it might be a running child or an approaching car....