AMEN! I keep seeing people say "Airlines are adding flights!" but not from what I'm finding. My United flight to Disney in July has been fairly stable - only one change on each flight that were not major - but I'm flying American to Nashville in August to visit my parents. I'm in NYC, so I can do JFK (preferred), EWR (less perferred), or LGA (last resort at the moment...MAYBE when their construction and AirTrain gets done it'll move up).
The August flight changed once - to Nashville went from a 6am-something non-stop to a 12:55pm nonstop, then the earliest; flight back changed to a later departure but a connection through Charlotte. Then this week I happened to check it (I usually check once a week but had forgotten to for a few weeks) and the 12:55pm flight had changed to a 4:55pm flight! Which had become the earliest non-stop!! That took a whole day away with my parents, which was NOT cool. I called and while I was on hold for 2 hours looked at my options so I could make it easier on the agent. Finally got it changed to a super-early flight out of EWR (5am!!) connecting through CLT to get there. The return flight thus far has stayed the same since its last change. Best part is they had yet to email me about it - and I know it had been changed a while because usually when it's in process it will give me a "Flights have changed, check back later for changes" but this time it was already done.
So yeah...DEFINITELY check your flights regularly!! I'll even be checking my return flights while I'm on my Disney and family trips to make sure they don't change mid-trip!