Steve is a hypothetical PC with 20 levels in Wizard and an intelligence modifier of +5, and as such he can prepare a total of 25 spells every day. He also has all spells a Wizard could ever learn in this spell book, due to a DM who is really generous in giving out spell scrolls.
One morning he says to himself: "Today I am going to cast something amazing, I just can’t decide what". So he sits down and prepares all possible 9th level spells and as many 8th level spells as he can in addition to that. Resulting in him spending 9 minutes each preparing 16 9th level spells (from the PHB, XGtE and TCoE) and 8 minutes each preparing 9 8th level spells. This results in him spending a total of 216 minutes that morning preparing his spell list.
When it is almost noon, he stumbles out of his room, hungry beyond imagination, down to the dining area of the local tavern, he is currently residing in. He is eager to tell his party members all about his amazing plan and finally eat his first meal of the day. To his astonishment his friends are nowhere to be found. They had waited for him for more than 3 hours, planning their whole adventuring day in the process. They are now on their way to kill that green dragon terrorizing the neighboring kingdom, with or without Steve.
"I made a terrible mistake" Steve mutters to himself. "I didn’t even realize how much time had passed. I must be the worst time-wasting spell preparer in tbe history of the multiverse."
But is he really the one who spend the most possible time imaginable to prepare his spell list or is there any way for a player character to spend more time preparing their spell list then Steve did?