Luggage: a positive.

My niece flew LOT yesterday to Zagreb through Warsaw. There was a 1.15 hour delay at Newark. She was traveling alone and nervous about missing her connection. There were four travelers on same connection. They actually held the plane 10 minutes for them, and all their bags made it too. That wouldn’t happen at too many airports. Was happy to hear this.

Our one backpack made it this week, too. JFK-Heathrow—CDG. It took a while to come onto the carousel due to the heavy flow of French people residents returing from vacations, coupled with airport employees off on vacation.
Note to tourists: the last half of August, planes and trains in France are full due to what’s called le retour, the return. So expect things to slow down.

One thing that I have done to assuage this problem is to book separate flights through separate airlines. I have better luck with baggage when I am on a direct flight. I will book a Delta flight from home to a hub in Europe and then claim my bags there. Then I will head over to the easyJet counter and check-in for my next flight. It is a little time consuming but no more so than a 3-4 hour layover. At least this way I worry much less about lost luggage. If you do this it's important to understand the baggage allowances for the airlines. I learned this the hard way when I was told at the easyJet check-in that my bags were too heavy since they don't allow as much weight as Delta.

Jack, your technique is more risky, because if that first flight is heavily delayed or canceled, you'll miss the second flight and have to buy a new (possibly quite costly) ticket.

And your bag could still miss the first flight.

Last Saturday we flew SMF-SFO-DUB and checked our carryon sized bags because we had a 9 hour layover at SFO and were leaving the airport during that time. Our bags arrived in DUB with no delay. We did put AirTags in them just in case. We flew United from SMF-SFO and Aer Lingus from SFO-DUB.