The sacraments are not magic, or medical treatments. They are encounters with God, and channels through which God desires to give grace.
As such, people can reject the grace that is being offered, even if they outwardly go through the motions.
Going to Communion does Nancy Pelosi no good, since she promotes mass murder and other evils. Each time she receives Communion, she commits another crime against Jesus Christ.
No; they are not.
My teacher always told us students to "Show your work."