Depends on the lane really. If the opponent must snowball, it's fine, just remember to play safe after that due to the lack of flash. If the opponent is still useful even from behind, meh, there's better targets to lock down, it may end up tricking you into overextending for no strategic gain. There are some matchups like TF where you should easily be able to dominate the lane without burning summoners even once, and there are matchups like Lissandra where you probably shouldn't have gone with Ignite in the first place. With that said however, when you bring Ignite, you are bringing ignite to win lane. It doesn't have the utility like Exhaust, Barrier, Cleanse, or TP could all grant post laning phase and unless you are 1v1ing a lot come late game (something that's much more difficult to predict, mind you) or you don't want to commit to Executioner's Calling to take down a healer, Ignite doesn't do much else than that. if you see a lane you know you can snowball against and shut down, bring Ignite and win lane hard. If you see a lane you know you can't hold down and you can see the game being decided by team fights rather than small skirmishes, probably should just lay off Ignite and use a utility Summoner Spell.
Now this is a looooooooooong topic when it comes to winning the game. Normally I'd refer to you Trick2g since he basically preaches the objective game, but he's a Jungle/Top player and I'm not sure if the skills used to carry games in those roles would apply especially to Yasuo. The (somewhat) shorter version is this:
- It's not a bad thing to take advantage of winning fights. It's a bad thing to commit to fights that do not make sense. It's largely contextual, again, but they're usually really obvious. For example, randomly catch someone in the middle of the river and Dragon isn't gonna spawn for another 3 minutes? Poke away if you could and disengage, get the kill if you can win the duel quickly and without any significant costs, but don't flash in ignite and try to all in right then and there. You are now without your summoner spells away from the lanes and towers and you can't even get dragon out of it, it doesn't matter that you won the duel and have a bit more pocket money to work with, that fight was dumb and learning how to play the macro game is recognizing why that fight was dumb.
- Everything you do needs to have an end goal. You want to play aggressively in lane? Make it a goal to either crush the opposing laner through efficient fights (say you only use one summoner while you crash through two of the opponent's summoners), zoning (it makes no sense to play aggressively in lane if you don't know how to starve the opponent as well), and/or destroying their tower long before they get to yours. Want to gank a side lane? You're an AD/AS champion and can easily chew through towers, remember to sit in the lane after a successful gank and shove the lane to tower; you might just be able to take it if you and your teammates work together. Think of it like this, you don't farm just to farm, you farm to buy items and scale up into a threat; there's a bigger goal to attain than just having done the action itself. If you fight, you aren't fighting just to fight, you fight so you can leverage an advantage from the fight. If you roam, you won't get anything out of just leaving the lane, you need to have actually done something while you left.
These two are the biggest principles of playing the macro game. If you learn what actions are dumb to overcommit to, it protects you from accidental throws and in general gives you a lot more resources to work with when it actually matters. Imagine if instead of burning both of your summoners in the middle of a river for no objectives, your summoners were a major factor in winning a 3v3 bot lane that turns into your team getting both a tower and a dragon, for example. If you learn how to turn random possibly advantageous actions into clear and definitely advantageous goals, you can snowball the absolute hell out of even the tiniest actions and turn into an actual monster by the end of the game.