Now that the EU right to repair rules are in force, repairability has moved from a virtue to a requirement — and, as usual, the cheapest place to deal with a requirement is at the schematic, not in the field.
Most of what makes a board repairable costs nothing. Reference designators printed on the silkscreen, and readable after assembly. Test points on the supply rails and on the handful of signals that tell you whether a stage is alive. Fuses and fusible resistors that are replaceable rather than soldered under a shield. Connectors instead of soldered flying leads between modules. Enough space around large electrolytics and connectors — the components most likely to be replaced — to get an iron in without lifting a neighbouring pad.
Some decisions cost a little and pay back heavily. Keeping the power supply on its own section so a fault there does not require dismantling the whole product. Choosing standard fasteners over adhesive. Avoiding parts pairing or firmware authentication that blocks a legitimate replacement, which is now a legal question and not only an ethical one.
And the part most often skipped: documentation. A schematic, a board layout, a note of test point voltages and a description of what each supply feeds turn a two-day diagnostic job into a two-hour one. Whether that documentation is public, given to the customer, or held by an authorised repairer is a commercial decision — but it has to exist, and it has to be written while the design is still fresh in someone’s head.