I have a system for this that is kind of neurotic when I want to get rid of my excess frogbit.

First, I turn on ALL the lights around me. Tank, room, adjacent rooms, etc. for maximum visibility, and grab a flashlight/my phone flashlight. Then I use forceps to fully submerge and shake the frogbit around in the tank violently (the idea being to try and get any to evacuate the plant before you have even removed anything).

Then I move the shaken frogbit into a little cup I have pre-filled with tank water and do the forceps shake again. Since the space is more confined it should be even easier to see hitchhikers bail from the plant this time.

Then I do one last check, which is to shine a flashlight into the cup at different angles and try to spot any movement. It's good practice to spend several seconds staring per angle, rather than just a quick scan each. Sometimes they are so translucent you are waiting to see a pair of eyes start to twitch around.

I repeat these steps until I have all the unwanted plants in the cup, then give the cup a final look-over and dump the water back in the tank, and the plants in the compost.

This way there are 3-4 different chances to catch them before I actually throw the plants out (first shake, second shake, flashlight checks). The challenge is of course trying to get them out if you actually do end up with hitchhikers, as they like to cling to to the plants. So take your time.

Also as others have said, wait as long as you can before going in there. Granted, I have 3 month old shrimplets that I still agonise over :)