Honestly, I avoid that approach. I don't reward at all. I also do not punish. My children are permitted at times to work toward something they want but it's over and above normal things they do that help sustain the household or do their studies, etc.
This is a quote from an interview with Alfie Kohn who has wrote extensively on exactly this. You can read the interview here.
HEL: What does the research tell us about the relation between rewards
Kohn: Rewards kill creativity. Some twenty studies have shown that
people do inferior work when they are expecting to get a reward for
doing it, as compared with people doing the same task without any
expectation of a reward. That effect is most pronounced when
creativity is involved in the task.
Rewards undermine risk-taking. When I have been led to think of the
"A" or the sticker or the dollar that I'm going to get, I do as little
as I have to, using the most formulaic means at my disposal, to get
through the task so I can snag the goody. I don't play with
possibilities. I don't play hunches that might not pay off. I don't
attend to incidental stimuli that might or might not turn out to be
relevant. I just go for the gold. Studies show that people who are
rewarded tend to pick the easiest possible task. When the rewards are
removed, we tend to prefer more challenging things to do. Everyone has
seen students cut corners and ask: "Do we have to know this? Is this
going to be on the test?"
But we have not all sat back to reflect on why this happens. It's not
laziness. It's not human nature. It's because of rewards. If the
question is "Do rewards motivate students? The answer is "Absolutely.
They motivate students to get rewards." And that's typically at the
expense of creativity.
Rewards undermine intrinsic motivation. At least seventy studies have
shown that people are less likely to continue working at something
once the reward is no longer available, compared with people who were
never promised rewards in the first place. The more I reward a child
with grades, for example, the less appeal those subjects will have to
the child. It is one of the most thoroughly researched findings in
social psychology, yet it is virtually unknown among educational
psychologists, much less teachers and parents.
He also had a number of books on the matter. In those, he does cite all of the various studies he is using to support his claims.
This does not mean I don't gift to my children. I do. I do it in the same manner I gift my spouse. I don't give my husband a nice tablesaw because he did a good job. I give it because I know he wants it and I love him and it will bring him some happiness. I don't go out and buy him a whole woodshop setup at once, even if I could afford it, as that is a tad much and would overwhelm most people. So I gift to my children the same way.
And it is just really a different approach overall. I might tell my children that if they finish their schoolwork quickly, we will have time to go to the park before dinner. The park is not a reward, it's real life. In real life, you can do fun things if you have time. If we needed to clean up before the park and no one did it, then we cannot go, because we ran out of time and that isn't a punishment. That is just real life, again. If we get to the park and one of my kids is acting off, then I will speak to them. If it continues I tell them we have to leave. Again, it's not a punishment. If it's a little one running, I explain that it's a safety issue and if they cannot be safe, I need to take them home where there is a fence to keep them safe. It's it conflict with other children, I tell them I recognize they are not in the right mood to interact kindly with others, so we can go home where they can sort out what is happening with their mood in an appropriate space to explore what has gone wrong.
So it's not that my children don't have good & bad outcomes to behavior, it's that it's taught through words, listening, connecting. I have found it to work well for mine.
My concern with a reward a day is that real life doesn't work that way. If every day I do absolutely everything I am supposed to, I may not even get so much as a "thank you" that I am not reminding the kids to give. No one is going to come give me anything for doing what I need to do. I think childhood is the foundation for life expectations. If you are given something every day at 4, what about at 5? How long can you sustain giving her something she wants every single day and afford it? When you stop doing so, will she internalize that as something changing in how you feel about her? If you never stop until she is grown, will she grow to be a demanding partner that wants to be cherished at a level most people aren't interested in sustaining?
I don't know the answers to those questions, they are questions to ask about "what could be the downside" to rewarding. They are the questions that led me to just not reward at all. I don't even reward with words. Instead I say things that mirror to them, asking their feelings. I ask them if they are incredibly proud of that accomplishment. I ask if they feel sad about how they treated their sibling. I ask if they are embarrassed about the way they acted at the park (with compassion, not finger pointing). I ask them if they can see how much they have improved with practice. I ask them if they feel super brave because they faced that fear. I focus on how they feel about what they do, because in life, that is your only constant. I can't be there all the time. No one can. When no one is, I want them to want to do their best still, even if no one can see, even if no one else cares. I want them to grow up internally motivated to do things that make them feel excited and proud and accomplished. I want them to know what those feelings are and to seek them out just for the joy of what that feels like. I also make sure they hear me tell other people awesome things about them on a regular basis. I try to avoid them ever hearing anything that remotely sounds like a complaint, even to their dad. If I have an issue, I talk to them (and discuss later in private if needed, away from their ears).