SpaceCadetLets be fair and objective here. Yes, hitting a dragon flying with 3 consecutive bolts is total bullshit and that death/scene was garbage but it was 2 very different situations.
Rheagal was flying into an "ambush" so he did not see the enemy, he was low to the ground, He was flying at a slow speed and lastly in a straight line. That made him pretty much the easiest target to try and hit. Still stupid to hit 3 bolts, but those are the facts.
On the other hand, Drogon was dropping from the sky like a Dive Bomber. In areal combat, "speed is life". Drogon was going insanely fast and he had his back to the sun which made him an even harder target to aim at or hit. Plus, he was going evasive and constantly moving around unlike the attack on Rheagal.
I agree that the situation was different, but why not show Euron baffled that he actually managed to hit the one in a million shot last episode, rather than hitting this extremely difficult shot 3 times, and then playing it off as being 'according to plan', before Drogon dive bombs at the ships (the same thing he did this week) before pulling away because 11 ships with ballistae are too dangerous to fly at. They set a precedent that ballistae are extremely dangerous to dragons in that episode, to then make them completely harmless the next. The 11 ships Euron had in the ambush last week also shot more bolts at the dragons than the entire fleet at king's landing (50 ships or so? Presumably equipped with ballistae) AND ballistae on every tower on the wall around king's landing. Note that all these ships and tower ballistae were on full alert and ready for Drogon to show up.
They also didn't show Dany and her crew take any account of this threat while planning the siege. A threat which was clearly significant since one of the dragons was just shot down. Their brilliant plan is to just dive bomb the dragon right at the enemy, something that was too dangerous to execute last week, and this time lo and behold, everyone missed.
This lack of consistency even within the same season is quite annoying. You either make it clear that ballistae are only effective against dragons when you hit the lucky shot and as such not that dangerous most situations, or you make them look like a real danger in both episodes. Now it just reeks of plot armour in one episode only.