What is considered 'bad' varies from person to person.
For me, skilling for over 2 hours per day, every day of the event, to collect enough in-game currency (twigs, leaves, embers, tokens, whatever) to unlock all the rewards, where missing even a single day will dash your hopes of completing the event, would be 'Bad'. Skilling for 30 minutes per day, in a much more forgiving event, not so much.
Where on that scale this new event will come, we have yet to see.
Uhh im sure you're still able to achieve everything even if you start on the last day.
Without buying MTX stuff or playing for an unhealthy amount, I've been unable to complete such "events" starting from the first day, with daily interaction... I absolutely loathe them and am very disheartened to see such a massive update like Fossil Island (or, at this point, just Island ) is preceded by one.
Ive only ever used the daily tools and ive always been able to complete it just fine.
Yes it might take more time but oh well but it is doable w/o buying anything.