I've taken a similar approach with my kids, but they're not really old enough to report back any results. I didn't round down to 1k hours or look at 10k seriously.
I've been trying to teach them that it's important to take the journey to get actually good at something. You pick up a lot of things on the way to becoming proficient.
I let my oldest pick something to get good at this year. She went with fast pitch softball. (she's 8)
She's threw about a thousand pitches the first month with me having her get out there. Since then (I thought that was too much) she's been the one to get me out there to catch her and that number has settled on about 500 a month.
With how many pitches you get in a normal little league (farm league softball) game, she basically pitched about 5 years worth of seasons over summer.
It'll be fun to watch this next season. I don't think anyone will expect a 4' 50 pound girl to throw as hard as she does.