If this ran the drop rate would be the same BUT it would simultaneously drop snowball type 1 snowball type 2 icicle red and blue soccer cards and ears and the like. You would have to do the 10 hours straight of 15 second but you’d get them all at once and have ample energy drops to get it done.
That actually did happen with the harvest event. It's a shame this type of review isn't part of the "events team" that would ensure the Inno events were properly reviewed so that previous achievements could be completed, and players wouldn't be overwhelmed with the event requirements - a players view of what Inno comes up with, instead of a dev writing code thinking they have the greatest ideas ever. Instead, from the events team, we receive additional events that only a fraction of the players participate in. And for the birthday celebration, if players didn't win in the special events, there were no in-game celebrations, or a bonus for a couple days like in previous years. Way to treat the players to a birthday! <slow clap for the current team>
Anyway, let's say a new char started in 2019. If the world events in 2014-2018 were achieved, those should be automatically applied to their profile since the world did achieve it. If there's a reward for it, maybe that doesn't get distributed since the char didn't actually participate, but at least allow the achievement to apply.