While looking at what round clubs started the FA Cup in, I discovered that Level 7 (Step 3) went up from 3 to 4 leagues and Level 8 went up from 7 to 8 leagues. Wikipedia says that in 2020-2021 Level 8 will go up to 8 leagues and Level 9 will go up from 14 leagues to 16 leagues so levels have twice as many leagues as the level above them.