Each crew has a lead tech and they have their own company card. Service techs have a card as well.
Our cards are actually debit cards that all have my name on them and it's a don't ask don't tell thing at the bank... lol. We limit the amount in the account but if we know they need to make a larger purchase, we can easily transfer more money into their account.
I would never expect my techs to use their own card and wait 3-4 weeks to reimburse. We also go to Home Depot frequently and everyone knows if they don't have a card (like a helper), they can go to the pro desk and they will call us for cc info (it's called a phone sale).