How often is October 1 a Friday?

It is either after 5, 6 or 11 years, depending on how leap years affect days being skipped. The last time was in 2010. These are the coming years for the rest of the century that it will be on a Friday and as you can see the gaps are either 5, 6 or 11 years:

2010

2021

2027

2032

2038

2049

2055

2060

2066

2077

2083

2088

2094

2100