Cable drawn from the van and never reached the invoice

Electrical work consumes material continuously and unpredictably. Vans carry stock so work is not interrupted, which is correct and makes the stock invisible.

Job sheets are completed later

Material used at ten o'clock is written down at five, if at all. What is forgotten is never billed, and it is disproportionately the small items that add up.

Reconciliation finds the pattern

Comparing what went into a van with what was booked to jobs shows the gap. It is rarely dishonesty; it is a recording habit, and it responds to making the recording easier rather than to instruction.