Well depending on the game... I will talk about a few games...
In FFX for an example, since save points heal you and your summons, and they were before every boss fight (and everywhere before a cut scene basically ) I almost never ever used any potions or anything unless it was just for someone to do something so they can level up.
and then in FFIV and FFIX (where characters had a set job and could only use certain abilities) I used a lot more potions and other things cause (depending on where you are in the game) the most is maybe 2 characters at a time can heal and you, so I ended up using a lot more potions to survive fights and stuff.
Then you have games like FFVI, VII, VIII, and XII where you could have anyone be a magic user or an attack user. In FFVI it just depended on what Espers you had them equipped, same thing in FFVII only with Materia.
In FFVIII like I said perviously most of the magic I only had for a short time just to Junction it until I got something better.
Then FFXII it came down to how you had characters set up in the Gambit system, but I did end up using a lot of items early in the game and didn't really stop using them until much later...
But as far as "saving" items and things, the only ones I ever saved were elixers...and I actually almost never used them at all ...
In FFX for an example, since save points heal you and your summons, and they were before every boss fight (and everywhere before a cut scene basically ) I almost never ever used any potions or anything unless it was just for someone to do something so they can level up.
and then in FFIV and FFIX (where characters had a set job and could only use certain abilities) I used a lot more potions and other things cause (depending on where you are in the game) the most is maybe 2 characters at a time can heal and you, so I ended up using a lot more potions to survive fights and stuff.
Then you have games like FFVI, VII, VIII, and XII where you could have anyone be a magic user or an attack user. In FFVI it just depended on what Espers you had them equipped, same thing in FFVII only with Materia.
In FFVIII like I said perviously most of the magic I only had for a short time just to Junction it until I got something better.
Then FFXII it came down to how you had characters set up in the Gambit system, but I did end up using a lot of items early in the game and didn't really stop using them until much later...
But as far as "saving" items and things, the only ones I ever saved were elixers...and I actually almost never used them at all ...