How does nuclear pull and shielding electrons affects ionization energy in the same period?

Going across a period, the effective nuclear charge increase (b/c you are at the same energy level "n" and you are adding more protons) so the electrons are harder to remove and the ionization energy increases. Shielding does not really affect the nuclear pull across the period b/c you are not going farther away from nucleus as you move across a period (you move farther away when you move down a group) you are staying in the same period just adding more protons which increases the pull on electrons and making it harder to remove electrons thus ionization energy increases.