Any of the above are fine. I would not be a fan of the "make a channel horizontally" method because of the destructive factor.

The "star" topology, one large junction box in the ceiling, is ideal because it keeps wiring length the shortest, just panel to box and box to receptacle. It is also the easiest if down the road you want to increase power capacity in there to run portable heaters, gaming PC, what have you.

The box needs to be large. You will need 4.5 cubic inches, plus another 4.5 cubic inches for each cable coming into it including supply. My go-to is a 4-11/16" steel box, which has 42 c.i. good for 8 cables. Big-box wildly overcharges, a proper electrical supply will have them for $2-something.

However, the attic junction box must remain accessible. It can't be "improved over" or if you do, you have to put a hatch there to allow access without disassembling any part of the building.

Any of the above are fine. I would not be a fan of the "make a channel horizontally" method because of the destructive factor.

The "star" topology, one large junction box in the ceiling, is ideal because it keeps wiring length the shortest, just panel to box and box to receptacle. It is also the easiest if down the road you want to increase power capacity in there to run portable heaters, gaming PC, what have you.

The box needs to be large. You will need 4.5 cubic inches, plus another 4.5 cubic inches for each cable coming into it including supply. My go-to is a 4-11/16" steel box, which has 42 c.i. good for 8 cables. A proper electrical supply will have them for $2-something, expect to overpay at a big-box store, which is ironic since you'd think they'd specialize in, well, big boxes.

However, the attic junction box must remain accessible. It can't be "improved over" or if you do, you have to put a hatch there to allow access without disassembling any part of the building. Also don't bury the box in insulation, it needs air contact to carry away any internal heat.