I don't let my students give excuses for not practicing. EVERYONE can get at least 15 minutes of practice every day (and even that is a pathetic time). If you are studying music it must be a daily commitment otherwise don't bother learning it.
Everyone can make time for piano practice there is absolutely no real excuse unless you are injured/sick or something tragic has happened in your life. Having too much school work or work work or family work is not an excuse, I always tell those students you can easily spend half an hour or more watching television, play computer or whatever every day you can easily spend 20 or so minutes of focused practicing your piano and the rest mucking around with it a little throughout the day. There is always time, so I always cringe when I heard that "I had no time" excuse.
Some pipe up and say but I have to study for school as well and at the end I am too tired to do any piano practice. I away say to them it is all in the mind, if I sat next to you with a million dollars and said you can have this at the end of your practice you would be all of a sudden awake and motivated to do your piano work. It is a matter of finding the correct motivation to suit yourself and keep you going. Why do you want to learn piano in the first place? Is it a task or is it a joy? It has to be both! Young kids see practice always as a task but they have to see what results they can get out of actually trying and sweating a little. Achievement is always a great joy and should be the basis of your motivation.
I tell kids, imagine that the piano is your favorite computer game, wouldn't you just love to get on it and play? Piano is just like that, it is a game, a board with 88 keys, we can press these keys in all different ways to make different sounds, something which can make people cry or laugh just by watching you play it. No computer game can ever do that. Most kids don't get it, but it gives them the idea, hey if the piano was like a computer game I would play it heaps more, so I better not say to my teacher I haven't got time. At least they won't lie to you and let excuses defend why they didn't do work.
If a student says to me, I was too lazy this week to do any work, I will accept the admission. It is not an excuse, they are admitting that they have been lazy full stop. Students start to feel stupid if they have to say this every lesson and start to feel motivated to show their teacher something new that they have learnt. I am always so excited when they do show me something new, mostly because it motivates them to do more and because I personally enjoy seeing them get somewhere! I always ask when we sit down with a student, so what have you got to show me today?
Some students I don't care if they do the work every day or not. Because it is a matter of their personal devlopment more than anything else. Doing piano every day is sometimes an impossible ask for some people because they don't really do anything that requires work every day! The idea of being committed to your work is something that is learnt, most people never get the hang of it, some of us stuggle through our whole lives to try and "stick" with something!
I know personally I am always forcing myself to sit down at the piano and get through my work (and music is my life but I have so many other interests which distract me (no excuse though

)), I do not naturally say with great joy, Oh yay another 50 bars of music to memorise I am so happy lets do this! It is a lot of work, physically and emotionally draining, but I love sound, I am extremely excited when I get the right sound, I also love the physical feeling of playing the piano and get very curious as to how to produce the right sound with minimal effort at the keyboard. So my mind is set, not worrying about the work but just working through what I need to do and observing what I learn. It is all about mindset and excuses are just a way to avoid setting your mind to a task. Human's are naturally lazy anyway so the sooner we realise we have to act against our nature here the sooner we will get off our ass and do some work.