SAN ANTONIO—Conversing with teammates during practice Friday, Spurs center Tim Duncan urged San Antonio’s players to be smarter with their frequent-flyer miles by accumulating the reward points for one big trip rather than squandering them little by little. “I can’t stress enough how important it is to practice restraint and never cash your miles for a domestic flight, even if it’s for a vacation,” Duncan was overheard telling guard Kawhi Leonard, at one point bringing the 22-year-old over to a whiteboard to explain how it was more prudent to save the frequent-flyer miles for a trip to an international destination. “Just remember to keep your composure and wait. You never know when an emergency might pop up and you’ll desperately need the miles. I also want to emphasize that if you’re not all using credit cards with miles bonuses, you’re missing out on an excellent opportunity.” At press time, several Spurs reported receiving emails notifying them that they had been shared on a Google doc titled “Tim’s Travel Tips” and a spreadsheet named “Budgeting Your FF Miles.”