How to flash perfectly in lane

I looked at a few Challenger streams to see if I can improve my lanetechnical skills and what struck me very often is that Faker, for example, flashs pure defensively only in rare situations, which is a big difference to me. In the vast majority of cases, an offensive Dodge-flash was responsible for 1-2 kills he could get with it, and in my opinion, that makes sense. If a skill is worth being flashed, then the opponent will get a disadvantage afterwards as this core spell will be missing for a while. Meaning, you have a relatively simple 1v1 fight in front of you, which actually always ends successfully with the quote: "Offense is best Defense". In many situations, Faker has won 1v2 fights by kiting one opponent and giving burst to the other. For example, Faker is Ryze and plays against Orianna , who is more Bot-oriented next to the Minions, and is ganked from top by Khazix . The moment Orianna presses Ult, he dodges that burst by flashing in her direction {{summoner: 4}} and places his rune cage on Khazix so that he can not engage. As soon as he can, he bursts Orianna with w + q, because he does not necessarily need his cage for this burst. Then he escapes along the Botside-river or can kill the Khazix and the Minions with the w + q combo. But of course semi-offensive flashs like those against Orianna + Khazix should not be the only ones. If you have no chance to successfully convert this flash into a kill, it should nevertheless be used to disengage, if death is thereby avoidable.

When I tried out how effective this is for me in significantly lower Elo, I had to realize that I could use it quite often successfully. In addition I have to admit that I usually play support, middle and sometimes ADC. In these roles, opposing core spells play a more important role than, for example, in a tank matchup, a la Mundo vs Maokai.

Now someone told me that those semi-offensive flashs can never end succesfully though i made different expearences, but she couldnt explain to me good enough that i could understand why she was saying that.