Ok. We don't necessarily need to go all the way down to new seconds. We can keep the hours in a day as is but have new months and weeks.

This is what I want:

12 months in a year

3 weeks in a month

10 days in a week

10 hours in a day

100 minutes in a hour

100 seconds in a minute

These new seconds are not the same length as regular seconds. I haven't done the math but it is possible to just make a second faster or slower.

Every year ends with a leap week of 4 or 5 days to adjust the calendar.