so i've been flying my Mini 2 for about a year and a half and just upgraded to the Mavic 3 Classic last month. loving it so far but im kind of lost on ND filters. with the mini i just used whatever came with the cheap kit i bought off amazon and honestly didnt pay much attention to it.

with the Classic though i want to actually do this properly since the camera is so much better. ive been reading about the 180 degree shutter rule and i get the concept but in practice i dont really know when to reach for which filter. like today was overcast and i had no idea if i needed anything at all or if i should still throw an ND on there.

also does it matter much if i go with the official DJI ones vs third party? saw a set from Freewell that's significantly cheaper and people seem to like them but i dont want to mess up the image quality on a camera i just paid this much for

Freewell is totally fine, i've been using their magnetic quick swap kit on my Mavic 3 Pro for about 8 months and honestly can't tell any difference vs the DJI filters in actual footage. the build quality is solid and the magnetic mount is way more convenient than screwing them on and off when the light changes.

for your overcast question - yeah you still usually want something even on cloudy days, maybe an ND8 or ND16 depending on how dark the clouds are. the whole point is just getting your shutter speed down to roughly 2x your frame rate so if youre shooting 30fps you want to be around 1/60. bright overcast can still blow that out without a filter. just check your shutter speed when you're hovering before you start a shot and adjust from there, you'll get a feel for it pretty quickly

im in basically the same boat as you, just got mine a few weeks ago coming from a Mini SE. the ND stuff was confusing me too but what really helped me was just watching a couple of Potato Jet's older videos on cinematic drone settings. he explains the shutter rule in a way that actually clicked for me. still figuring it out in the field though tbh