4 gal per day for the 29 gal would equal roughly 65% per week
3 gal per day for the 20 gal would equal roughly 68% per week
So, yes it would be more than 50% per week if that's what you're asking.
10% daily would be 10% of the overall tank volume. Also as an example: Consider your fish producing 2ppm of nitrate daily.
To make this simple lets say you have a 100gallon tank with another easy to work with number of 100ppm of nitrate.
10% of 100g is 10. Now you have 90(+2 for daily production of nitrate for your fish)
10% of 92 is 9.2 now you have 82.8+2
10% of 84.8 is 8.48 now you have 76.32+2
10% of 78.32 is 7.83 now you have 70.49+2
10% of 72.49 is 7.25 now you have 65.25+2
10% of 67.25 is 6.725 now you have 60.5+2
10 of 62.5 is 6.25 now you have 56.25ppm
7days at 10% would only be giving the impression of 70%
50% of 100g is 50g =50ppm. Which would cut your nitrate in half.
Long winded and theres probably an easier way to work it out mathmaticly but the idea is the same.