We basically took the view of having them do one sport which they can enjoy for a lifetime (and not just up to high school or college or while their bodies are young), one basic instrument (to develop an appreciation and understanding of music - doesn't have to continue beyond a certain minimum proficiency as they aren't going to be playing in Carnegie Hall) and one 'other', which could be a language/art/science/competitive game, etc. It's averages out to about an hour total a day per child time commitment.
I would have thought that once they get older they would have less time as the school day is longer, homework load is greater (at least if they are getting a decent education), social activities (including just 'hanging out' with friends) become more pressing as well as interests in other stuff they would like to do on their own. Giving them a minimum foundation in some of the basics in life (that one might actually want to appreciate or pursue if one were to ER) other than school and work seems like a nice thing to give a child, no?
So, if I understand your statement above, I have some questions.
1) You will give them lessons in one lifetime sport.
- What if they develop interests in a team sport or other activity? What if they show interest and aptitude to compete in that at a high level? Are you going to say, "We provide lessons in [insert golf, tennis, skiing], you are on your own if you have any other interests." If they become really good at [], will you shell out extra for professional lessons, camps, and etc? If so, your current level of spending will not remain the same.
2) You will provide lessons in one instrument (picked by yourself?) to a point of minimum competency.
-Same question. What if they want to try the harp? Harps are in the tens of thousands and teachers are rare and expensive. Do you say no? What if that is their dream instrument? What if they are really good and have a chance at Carnegie? Will you restrict your lessons to a certain level or will you pay to see how far they can take their talent?
I am the mother of six kids from 20-yrs old down to six and I can assure you that you are currently in the "cheap" years of child-rearing. I am currently putting kids #4 and #5 in braces (#6 is too young, but will need them too). I have two kids driving (cars, insurance, gas) and one with his permit. We have let the kids try different sports and activities and have supported them in their interests and aptitudes. This means one has played on club volleyball teams which we have also had the expense to travel and watch her. She has gone on to play D1 volleyball on scholarship. We have one that loves football and wants to play at college. So we have done college summer camps, nutrition counseling, and speed and agility training. The next kid is a musical (and academic) genius. He plays piano and guitar. He has had lessons at a very high (and expensive) level, but has decided to stop lessons at the moment. He is pursuing activities to become the language Sterling Scholar and wants to do study abroad. He also skis in the winter and golfs in the summer. And on down... What I've learned is that despite have the same two parents, each child is completely unique. They are influenced by us at young ages, but make their own decisions and have their own unique personalities.
So what is our goal? To make them the most successful? Nope, It is to lead them to a happy, fulfilled life. In our opinion, there are a lot of things that lead to a happy, fulfilling life. First, I believe they need a happy family life. This includes a lot of time with parents and siblings. Second, they need a spiritual backbone. Our kids learn about God at home, in church, and at mid-week church activities. Third, they need to learn to serve. Service activities are often woven into church activities and home life. Fourth, they need to understand the importance of obtaining an education and preparing for a career. And fifth, they should be supported (within reason and financial limits) in their interests and talents. We believe that talents are given to us to share with others, bringing happiness to others and self. Our financial goals to become FI are important, but second to our responsibility to the children we brought into the world. Of course, as others have stated, balance is a key word. And MMM's idea of optimization is important too. I know of a family with limited resources that still found ways to provide sports and enrichment activities. If you believe private school will make their lives more happy and fulfilled than if they were in public school, then you may justify that expense. On the other hand, you may find that golf lessons at the local public course are less expensive than at the fancy country club, and the enjoyment is the same. That might be an opportunity to optimize. Make a list of your goals and values, look at the costs- both current and projected, decide which will really lead to happiness, and be flexible. Those sweet little kids will soon have a mind and an agenda all their own. And they might surprise you.