I save my stamina potions for events. . and then use them on Mondays for the week of the events. .
or you c*e them for the monthly event things. . .
I mean, make the most out of them, right? With the monthly events, you can get more threads. . .
Especially if you are f2p, you have to be patient and make wise decisions.

You c*e your potions however you like. It's YOUR gaming experience. Don't take everything people say on here as absolute. People say all the time to only pull from Kage treasure....who's gonna stop me from pulling from any other treasure? Nobody lol. Play the game how YOU want to play it, if you wanna use the potions then use them.

It is up to you whether you want to use your stamina potions on Monday or not. For me, I would save them for monthly events where you c*e those points to redeem refine runes. :D

Which ninja fragments do you collect that is taking so much of your stamina? lol. . .
And it shouldn't be forever. . .I mean, once you hit 4-star or 5-star. . . eh. . .

why refine runes over threads?

I save my stamina potions for weeks 2 and 4 for the monthly event (where you have to sweep 60 plot/elite instances).

If you want to, use all your stamina pots right now. I guess if you want to assume our suggestions and examples as absolute, divine commands to shove our ideals down your throat, you can do that.
Who cares about missing all of those monthly event points AKA threads and runes, right? Who cares about using them for juicy events like Ramen Event or Character Plate events in the future that may hold even better rewards. Lol, after all, these suggestions are just us forcing our ideas down your throat and not us giving you advice on the most efficient and smart ways to use stamina potions.

This is WHY you're falling behind as a f2p. You have to make decisions wisely cause we don't have the budget or chances like those spenders.

I spent 20 scrolls on Seal Treasure when I first started, and another 20 on Tendo treasure and I really regret it by now. I'm lvl 67 atm, I could have saved 40 seals for the kage treasure which will unlock at lvl 70.

In Kage treasure, at least you can draw useful ninjas even though they aren't rare as contrast to common Seal Treasure or Tendo treasure. They aren't totally useless.

Patient is the key for f2p.

You can only fall behind as a f2p if you actually care about being the best, which you already decided not to be when you chose not to be a payer. I'm a f2p and it would be insane for me to even THINK I'd be able to keep up in a game that caters to people who spend. I'm on S2 and the only chance I'll ever have at keeping up is if all the payers stop playing. To me, f2p should be about playing because you enjoy Naruto. Paying is enjoying Naruto and wanting to be the strongest since all games like this are designed that way. So, if you AREN'T serious about this game, you don't have to budget squat. If you ARE serious, then budget and do what others say.

You c*e them on Mondays for double exp or when theres an event that requires you to sweep instances, either way its your choice and decison on when or where to use them.