if you organise your pax at the gate they will have p.p open at picture and boarding cards ready
step 1. look at pax as they approach
step 2. look at boarding card, move eyes down you will be checking name with in 2 second time span, you have already looked at pax and so can verify they match picture.
step 3. pull boarding card hand to pax and away they go...
Don'y forget step 2a. check for correct flight number and date...
Or you could end up with...
step 4. do a count... one over and a load of hassle!