They can happen at instant speed, so if you have a fetch land like Wooded Foothills or a way to put a land into play at instant speed like Harrow or Sakura-Tribe Scout, you can get the trigger at instant speed
A: Each booster pack contains 9 cards
The Crystron archetype consists of WATER Machine monsters whose non-Tuners involve destroying cards, setting up for their Tuners to Synchro Summon during the opponents turn, or adding consistency
Lastly, if players could swap say 3 copies of a lower evolution to get a single copy of the next stage card, it would be a real game-changer for many players as there is little reason to play the lower evolutions without the final stage unlocked
Booster Box (YuGiOh Japanese Enemy of Justice | YuGiOh Cards) prices are based on the historic sales
Admittedly, this isn't as much of a hindrance as it may initially seem, as you'll likely be playing only one or two copies in your sideboard and won't often have multiples in your hand, much like Relic and Lantern