Now adays it is easy to find guns like the Ruger American Rifle that come from the factory with bedded actions, free floated barrels and adjustable triggers.
When I first started buying bolt action rifles, there were no such things. Trigger pulls were commonly about 6 lbs, actions were not bedded but were just inlet into the wood, and almost all bolt actions came with fore-end contact at the front end of the stock. If the temperature or humidity changed, or if you used a bipod to varmint hunt, your point of impact would change.
Brownells Acraglas became my friend for bedding actions, which then allowed me to free float the barrel. My friend (a part time gunsmith) reduced the trigger pulls to about 3 lbs for me.
It did not always improve accuracy, but it did make them easier to shoot accurately and far more consistent, especially if varmint hunting with a bipod.
Judging from the # of aftermarket triggers I see for sale I don't think my problems were unique.