Is there increasing benefit for every additional hour after 16 hours?

(a) If I fast for 2 hours from 18 - 20 hours or (b) for the 2 hours from 34-36, then would the 2 hours fast in the case of ( b) 34-36 have a greater effect than the 2 hours from ( a) 18 - 20

Because often at 20 hours, i tell myself that fasting 4 hours more from here onwards will give me much larger benefits instaed more sense than doing another 16 hour fast tomorow . Is that true ?