To me I don't really care about the certificate lifetime, what I care about is the time between being allowed to renew and time until expiry.

Right now Let's Encrypt recommends renewing your 90d certificates every 60 days, which means that there is a 30 day window between recommended to renew and expiry. This feels relatively comfortable to me. A long vacation may be longer than 30 days but it is rare and there is probably other maintenance that you should be doing in this time (although likely routine like security updates rather than exceptional like figuring out why your certificate isn't renewing).

So if 47 days ends up meaning renew every 17 days and still have that 30 day buffer I would be quite happy. But what I fear is that they will recommend (and set rate limits based on) renewing every 30 days with a 17 day buffer which is getting a little short for comfort IMHO. While big organizations will have a 24h oncall and medium organizations will have many business hours to figure it out is sucks for individuals who what to go away for a few weeks without worrying about debugging their certificate renewal until they get home.