The kids who are gifted and interested in math can learn the material in a few hours/days whereas the math material is broken down to be taught for 3 weeks!

Some kids are very fast after they learn the material and able to calculate, I would guess these may be the PG and HG kids.

Some kids understand the math but are slow in calculating the answer but given the time, they can come up with the correct answers. I would guess these may be the MG and HG kids.

Depending on the child, some MG - HG kids can probably be accelerated 1-2 years to get some challenge. The HG-PG kids can probably be accelerated 2+ years and I wouldn't be surprised at 3-5 years. Not just skipping but more that the pace of delivery can be increased.

1st Grade to 5th Grade Math is pretty basic.