Why rework causes problems
When the invoice is typed fresh into a separate tool, small things drop off: a part fitted late, an extra half hour, a discount agreed verbally.
Each omission is minor. Across a month they add up to real money.
What reduces disputes
Record additional work when it is agreed, keep the parts on the job, and issue the invoice while the detail is fresh.
A customer who has already approved the extra work rarely argues about it at collection.
Invoicing promptly
Invoices raised days later get queried more often and paid later. The closer the invoice sits to the handover, the simpler the conversation.