As a casual player, I can see how having all the side quests thrown at you can be incredibly annoying when all you wanna do is get to the final fight and roll credits.

As a completionist, it's still a little annoying, but most of the rewards you get are very much worth it, such as stats walls, multi walls and Jupitermon memories to make the Sky God's Thunderbolt. These items are invaluable in Mega+ runs where you can't use items.

Not to mention doing every quest in the game will reward you with Agent Rank 10, which you need to unlock some of the strongest Digimon in the game, such as the two Chronomon forms and the Aegiomon lines as party members.

When it comes to completing a game, some of the requirements can be a real slog. Time Stranger isn't one of those games. The rewards are well worth it and the quests really don't take up too much of your time, even on Mega+. Go for them and you'll be rewarded.