Saying not to bother is very bad advice in the long term.
I'm 100% with Ihateautofraud above. Don't be lazy. Drop the pan. Install the magnet. If you took your car to a shop and the tech forgot it, you'd rightly demand the owner do it right. YOU owe YOURSELF the same quality work. Not having it installed won't be a problem today, tomorrow or the next day, but sooner or later....
Why? According to John Eleftherakis and Abe Khalil, did a series of studies for the OE trans manufacturers and the aftermarket that started in the late '80s, and continue to today, the contamination makeup of the average transmission oil is 90 metallic. Of those metallic particles, 51 percent are ferrous (iron/steel), 21 percent copper, 11 percent aluminum and 7 percent lead. The particles range in size from 5 to 80 microns, about 82 percent of them larger than 5 microns. The pan filter is no better than a 60 micron... a very few get down to 40. The issue is that the solenoids in the trans are nothing more than electromagnets, so as your trans generates ferrous metallic contamination, those are going to be the places where it collects. That's why the pan magnets are there in the first place, to try and catch them before the solenoid does. It's a cheap OE way to get the trans out of warranty. The bare minimum, as was stated above. Transmissions really need better filtration and why I have a cooler line magnetic filter on every automatic I own.
As an aside, I recently cured a slip-bump problem on my 4T65E by installing a Magnefine cooler line filter. The vehicle is fairly new to me and while I had changed the trans fluid, the Magnefine installation was a bit more challenging and I hadn't gotten 'round to it yet. It began doing the notorious slip-bump, typically cause by a"fuzzy"(with steel) PCS and that would have eventually killed it. Got off my dead butt and installed the Magnefine. It did it a couple more times and then stopped. Four months now without a relapse and it was starting to do it about every other time I accelerated from a dead stop.
Some say an inline filter/magnet is better than a pan magnet because too strong a magnetic field near the electronic solenoids can interfere with their operation. I don't know that to be true but there is some logic to the idea anyway.