"Sometimes leaks can trickle down and cause issues in spots you wouldn't expect."
This is spot-on. Had a client once who patched a small leak himself with some random sealant he had lying around. Thought he was good to go until months later when his ceiling started discoloring two rooms away—water had traveled along beams and insulation. DIY's great for lots of things, but roofing can be sneaky. Better safe than sorry...and cheaper in the long run.
I learned this lesson the hard way myself a few years back. Had a small leak near my chimney, figured I'd watched enough tutorials to patch it up. Got some roofing cement and slapped it on there, job done—or so I thought. Fast forward a couple months, and I'm noticing damp patches forming around a window frame downstairs. Could not figure out what was going on, because the roof above that spot looked totally fine.
Turned out, water was sneaking in around my amateur fix, running down behind the siding, and popping out again further down. Took a pro roofer to point out exactly where I'd messed up. So yeah... DIY roofing vids can be great for quick visual tips, but they're no replacement for someone who knows how water behaves and travels under shingles and flashing. Learned my lesson that day—if you're not 100% sure where the water's coming from or how to properly seal it off, probably best to call someone who does. Cheaper than repainting half your living room ceiling, trust me.