Can you run a junction inside an outlet or recessed light
According to the National Electrical Code (NEC), there are only two factors that limit you.
Conductor box fill
If you're working with standard sized boxes, you can use Table 314.16(A) to determine the number of conductors allowed in a box.



If you're using non-standard boxes, you'll have to make the calculations yourself. Basically, it works like this.
Conductor Fill

For each current carrying conductor (ungrounded (hot), or grounded (neutral)) that terminates or is spliced within the box, add 1.
For each conductor that passes through the box without splice or termination, add 1.

Clamp Fill

If there are any internal cable clamps, add 1 (not 1 per, just 1).

Support Fittings Fill

If there are any luminaire studs or hickeys, add 1 (not 1 per, just 1).

Device or Equipment Fill

For each yoke or strap containing one or more devices, add 2.

Equipment Grounding Conductor Fill

If equipment grounding conductors enter the box, add 1 (not 1 per, just 1).

Volume Allowance Calculation
Use this Table 314.16(B) to calculate the total box fill.




Sum up the count from the Conductor Fill section, and multiply by the value from the table.  For example:  If you had 4, 14 AWG conductors, you'd multiply 4 by 2.00.
Sum up the counts from the Clamp Fill, Support Fittings Fill, Device or Equipment Fill, and Equipment Grounding Conductor Fill sections, and multiply by the value from the table of the largest conductor in the box. For example:  If this value was 4, and the largest conductor in the box was 12 AWG. You'd multiply 4 by 2.25.
Add the 2 totals together. For example: Using our values above (4 x 2.00 + 4 x 2.25 = 17), you'd need a box with a volume of 17 in. cubed.

Wire Connector Capacity
If you're using twist-on wire connectors, each connector can connect a specific number and size of conductors (Check manufacture documentation).  This will limit the number of wires connected together.  If you're using push-in wire connectors or terminal blocks, you'll be limited by the number of terminals.

tl;dr
If you want to supply multiple devices downstream; but the devices are in opposite directions, there should be no problem splicing multiple cables together to feed the devices.