Retired union pipefitter/welder here, I started working in the trade in 1969. At that time our week was 35 hours and all overtime was at DOUBLE. Plenty of opportunities to get OT and OT pay being double the money and many hours brought a nice return. We had a bunch of BIG chemical and manufacturing plants in our territory so money and hours were plentiful. Of course most of this work was outside in upper NY state so weather conditions made a lot of that work rather difficult and sometimes dangerous!
Back about 1990 we went to a 40 hour week and all OT at 1 ½ per hour except for Sundays and holidays which remained DOUBLE. Still plenty of money and hours to be made if you wanted to work serious hours. I have many weeks of doing 7-12s (occasionally more hours) and raked in some serious money though being totally honest it phucked up my health and I took early retirement at age 55 (as normally retirement is 62 I had to take a reduction in pension benefits for leaving early)
With that said every hour I worked and some hours counted as double I had a chitload of credits in my pension when I left even with the early out. All those extra hours gave me an extremely good pension with good health benefits + SS have allowed me to enjoy a very nice upper middle class retirement.
Wife also has a good retirement package and retired a couple years after I did.