Key Takeaways:

Kids who tend to be disorganized and have a poor sense of time often have what's called a soft internal clock: they have trouble judging how much time is going by or how much time they really need to get their work done
To help with this, we can give them an "external" sense of time with a clock or timer to give them that extra "umff" to get started and stick with it

Action Steps:

Try getting a Time Timer (or something similar) to set up in your child's study area.
Employ the "Tolerable Ten" technique with your child and set the timer to 10 minutes. Explain to them that they need to focus and put in their best effort for that full 10 minutes, and at the end they can decide to either take a break, or keep going.
Experiment with other longer and shorter time durations until they get the hang of it (making sure to never set the timer for more than 30 minutes at a time). Then, leave it in their study area for them to start using independently.