Agreed. Learning which spells and weapons to attack tough monsters with and remembering when to use what after obtaining them can be very rewarding as is the process of getting them because you know they will be needed. That doesn't work out so much when players can expect to just use their default go-to thing with good results for all opponents.That would suggest you are also against high Armor Class, all energy immunity's, condition immunity's, spell immunity, etc.
Uncovering an enemy's weakness, weak spots or vulnerability to exploit should prove rewarding. Likewise expecting all your tactics should simply just work on every enemy sounds like complacency the GM should punish now and again.