Are there any disadvantages of having many solder joints on a single wire?
Multiple exposed joints that need to be heat shrunk or tapped up. A broken jacket in multiple places causing the wire to be weaker. Even daisy chained crimps or solders make the wire weaker. A mess to fix if you need to in the future. And worst of all, it looks ugly and unprofessional.

If you need to solder multiple times to the same wire, consider using an in-between, like a terminal strip, or a pcb, or something solid. Or use more wires to the board. Look at professional pcbs like in ATX Power Supplies. Multiple wires needed to the same supply? Multiple wires to the board. The only wires that are daisy chained are the power to the hard drives, and those are professionally crimped and soldered.



A non standard splitter (too many connectors) but the general idea:



Also consider other means of connecting the wires. Crimping, Taps, Spade connectors, even Screw Caps. Soldering isn't the only or even the best method.