I am a poll worker in NYC.

Our training was changed, and if followed to the letter, would create long lines.

The old way was to issue a card to each voter to wait on a line creating two comfortable lines. If challenged that voter could step aside and not hold up other voters, then sign the challenge oath.

The NEW way is to hold that card on the table. Logistically it creates a lot problems.

If you lineup the cards in the order of voters on the line and people move around. It increases the possibly of people voting for other people, maybe twice. If you issue only one card at time, you have created a long line of people just waiting to sign the book (and possibly a vacant booth). People for many reasons may not have their names in the book possibly holding up the longer line. People simply may not be on the right line for their ED and AD.
Voters might have had their first and last names reversed, changed
their name or just by the incompetency of the worker looking up the
name. A voter might not have voted often enough to remain on the voting rolls and use the option of a provisional ballot.

This is were it gets very serious! Valid voters whom for all the wrong reasons had their names taken off the list (purged).
Worse still voters on the rolls being wrongfully challenged! Voters
might have moved, too recently to re-register at their new site (recent
foreclosure). Voters whom happen to have a name similar to a person not
eligible to vote. There is no real penalty for a wrongful challenge, except after the election is over. After being challenged the voter signs the challenge oath and votes, but not before the challenge evildoer holds up the line for as long as they can. Doing
preprocessing of potential voters may help shorten the line, allowing
voters on the wrong line to find their booth and purged voters to vote
by affidavit (provisional) ballot. Realistically there is no way to stop this tactic (using the new way), the challenger would wait until the voter was about to sign.

The old and new way still allows the extremely few people whom
fraudulently voted to be prosecuted after the election as well as the
wrongful challenger for false witness.