a good way to detect disconnections on the PCB traces
The problem of broken (or shorted) traces exists in any (especially DIY) PCB fabrication technology, whether toner transfer or high end photolithographic film process - The difference being the trace widths affected, of course. 

Validating trace integrity of multiple boards can be done in a DIY environment by using a home-grown bed-of-nails testing rig, consisting of a bunch of pogo pins on a rigid base, and perhaps a row of LEDs to indicate respective trace continuity. 

 (source)

Adafruit has a tutorial on how to set this up.

If it is for a small run with through-hole part spacing and 0.1" trace distances, and the rig is unlikely to be needed again, a functional bed of nails can be set up using a breadboard and some effort.



Even the most expensive fabrication facilities have at least random sampled board integrity testing as an offered service. If anyone tells you a technology change will guarantee no more broken traces, they are merely advocating their preferred approach, without basis in fact.