Standing on the block does not put you in a good position to see lane violations or displacement in the lane on free throws. The approved position in the NFHS and CCA Men's Basketball manual does. This is an article that explains more about why you should not stand in the lane as the Lead
Lead, They Didn’t Vacate that Lower Lane Space for You to Stand In. See
https://www.myvirtualofficialsassociation.com/?p=626 for more information on stopping the clock. The reason why the NFHS and CCA men's manuals require stopping the clock is because the "stop the clock" signal is what technically stops play, as well as reminds the clock operator to stop the clock, and gives the official time to process the play before making a decision.