If you would stop reading those percentages as an overall chance to get to the next star or saint it would stop bothering you.

The percentages are teh chance for THAT ATTEMPT and tha ATTEMPT ONLY to succeed.

Look at it this way

Take a bag
put 100 marbles in it.
say 80 black and 20 red

Draw a marble out of the bag.
You have a 20% chance to get a red
Now if you draw a black what happens?
Many people want to leave that black out of the bag and draw again. Which changes the % and not how stars and saints work.
Instead you must put the black one back in the bag and draw again with 80 black and 20 red in the bag.