This is something I never understand. Before I do anything major i always save my game, and anything minor I quicksave. Pokemon Blue taught me early the hardship of not saving.
I save periodically but consciously when I'm about to try something silly. Like when I noticed flammable containers are actually pressurized and flammable in this game. When I knocked over a propane tank and startled a very, very angry Feral Roamer (I was level 1 on survival, don't judge) and he preceded to eat my face (cool addition to NPC kills on you), I took a step back, saved and pulled that propane tank out of the building into the open.
First, I shot the nozzle off. It flew off adorably, bouncing around until it exploded.
Second, I shot it twice in the body, it went boom.
Third, I placed if across the door as a trap, lured the Roamer out and blew it to hell with the help of my environment.
And that's when I realized I can adapt Half-Life 2 problem solving to Fallout 4. Thank you Bethesda for making your world more robust, interactive and intuitive!