Your children are generally in school for about 6 to 7 hours a day. Not all of that time is spent on school work and instruction. The benefit to working with your kids one on one is that you are able to maximize your time and theirs. Instead of doing a traditional 6 hour day of school, instruction time and one on one work can be cut down to about 4 hours of work.
Now, if your kids are older, the amount of time that they will need help with will be a lot less compared to a child who is younger and needs more help with reading and directions.
If you find that your child is getting all their work done very quickly either one of two things are happening. Either their lessons are easy and they understand what they are doing. Or, they do not necessarily care and just want to get the work done quickly. This is something you will just have to be aware of and adjust accordingly. If they are legitimately just mastering their lessons, see if any of the free resources adds a little difficulty to their studies!
My brother recommended I would possibly like this blog. Germain Richardo Hiltner
Thank you for your kind words. Have a fantastic new year!