I'm glad someone made a thread about this cause it's actually bothered me a bit in the past when my opponents spent time declumping their deck, because this then forced me to waste even more time randomizing their deck for them. Just inefficient time management and it could absolutely affect the outcome of a game. Re-randomizing your deck and spending a total of about a minute doing so (which by the way, is for no reason, because your deck was already random to begin with) effectively reduces the amount of time you can spend playing the actual game, so its just one player being a jerk and wasting his and his opponents time.
Picture yourself playing Pokemon Collector on the 1st turn of the game and noticing 3 Junk Arms and 2 Yanmegas all stuck together. You declump your deck and your opponent shuffles it for you. The following turn you play a Pokemon Communication and fetch one of those Yanmegas, but notice that there's now 2 Judges and 3 Copycats stuck together, you think "hmm... weird, why didn't I catch this before?" and declump again, your opponent shuffles your deck and you continue playing the game. A couple of turns later you search your deck a third time and now your Junk Arms are all stuck together AGAIN, what gives?! You AGAIN de-clump your deck and your opponent AGAIN shuffles it for you. The following turn you play a Pokemon Collector, attempting to reduce your hand size to match your opponents, you look through your deck and grin as you see no discernible patterns, you did it, you beat the game. You give your deck a nice shuffle and continue playing the game.
In this admittedly extreme example, you (you, by the way, is nobody specific) wasted about 3 minutes of yours and your opponents time. What people don't understand is that shuffling a deck correctly will always randomize the deck at the end. You could very well spend an entire minute randomizing your deck after declumping 3 Junk Arms only to shuffle them next to each other immediately after.
Picture yourself playing Pokemon Collector on the 1st turn of the game and noticing 3 Junk Arms and 2 Yanmegas all stuck together. You declump your deck and your opponent shuffles it for you. The following turn you play a Pokemon Communication and fetch one of those Yanmegas, but notice that there's now 2 Judges and 3 Copycats stuck together, you think "hmm... weird, why didn't I catch this before?" and declump again, your opponent shuffles your deck and you continue playing the game. A couple of turns later you search your deck a third time and now your Junk Arms are all stuck together AGAIN, what gives?! You AGAIN de-clump your deck and your opponent AGAIN shuffles it for you. The following turn you play a Pokemon Collector, attempting to reduce your hand size to match your opponents, you look through your deck and grin as you see no discernible patterns, you did it, you beat the game. You give your deck a nice shuffle and continue playing the game.
In this admittedly extreme example, you (you, by the way, is nobody specific) wasted about 3 minutes of yours and your opponents time. What people don't understand is that shuffling a deck correctly will always randomize the deck at the end. You could very well spend an entire minute randomizing your deck after declumping 3 Junk Arms only to shuffle them next to each other immediately after.
