Im really focusing on SH2 here cause I cant remember the first one and I know the third one was just focused around surviving and running away.
There was allot more puzzles than "open the locked door" for example
Spoiler:theres something jammed in the trash shute and to get it out you need to drop a six pack of orange juce down to knock it out.
and as for monsters, I cant remember there being that many in SH2, you could be running around the town for ages and never run into a monster, and even if you did you could just keep running and they wouldnt catch up to you
And I didnt think of the puzzles as being poorly intregated, they were just fine.