They should've never made the USB 3.0 internal cable that long, because most motherboards got the USB 3.0 internal port on top-right or mid-right side of the board. Better to rather offer an extension cable to make it longer, if needed.
For my cable management, I custom ordered a 7" and 10" ATX 24 pin cable. Just to test both lengths. I think I could've even been okay with 5" ATX 24pin cable. Also got 2x 12" 4pin EPS cables and 2x 12" PCIe 6+2 pin cables. I could've gotten them shorter, probably to 9" for the EPS and 3" to 5" for the GFX. Now my ATX PSU is 200mm (7,87" approximately 8") long. The EPS connectors are on the very last corner of the motherboard, right before the rare I/O on the motherboard. So just to get passed the PSU to the connector would at least require 8", then another inch just to get the flexibility to connect it. For the GFX PCIe cables, the GFX is right beneath the PSU, utilising the PCIe Gen 3 x16 slot. I could just plug it in from top, then straight to the PSU. But I was thinking to route it from beneath, then up to the PSU connectors, so it would look better. Regardless, they could be shorter than 12".
The measurements of the cables do not include the connector length on the cable ends.
If someone wants to do the same as me, then they would want to consider this. A complete modular PSU is an absolute must, in this case.