I'd much likely prefer server time based cooldowns. At least regarding digging spots. It would make it way easier to keep the track and be more efficient. Players who can't log in at a special day might not be able to farm digging spots efficiently. They would lose a day, because they simply weren't able to play due to whatever reason it might be. Therefore the 3 days-cycle is going to be broken and you need to wait 2 more days to be in your regular schedule or change it. Making digging spots server based would max out the efficiency of farming and giving the player 3 possible days to do it. Personally i would feel way less forced to login on exactly that one day "just" to do lame farming. There are days where you just don't like or are able to play. On the other hand, bosses should stay expire time based or eventually get their cooldown cut by half in case you lose, but that's just a very comfort change and i don't think that it's necessary, though it's still worth mentioning since it would not give any advantage to some players.