We started with HVAC shops that were running their whole operation out of text messages. Jobs got assigned in a group chat, customer history lived in three different places, and invoices went out days after the work was finished.
So every screen we built had to pass one test: would a tech with dirty hands actually use this? If the answer was no, we redesigned it.
That's the whole product philosophy. Fewer fields, bigger buttons, nothing your crew has to be trained on.