The last time the Giants played six games in a row against the same opponent was 1969, against the Braves at Candlestick Park. A four-game series became a six-gamer because of a scheduled Fourth of July doubleheader and another two days later caused by a rainout.

The Giants won four of the six, a result they gladly would accept – but will be hard-pressed to replicate – when they end the first half with three home games against the A’s then start the second half with three in Oakland.

Friday night’s game at AT&T Park begins a stretch that will be as important for the Giants as it is challenging.

Ownership and management need to decide their direction ahead of the July 31 nonwaiver trade deadline, whether to sell, buy or do both, based on where the team stands.

The Giants have 14 games left in July, and the first 12 are against three of the toughest teams in the majors: Oakland, Seattle and Milwaukee. Yes, the Giants pitching staff has been gangbusters, but those three teams are extraordinarily dangerous at the plate.

The A’s are dangerous, period. They just took three of four in Houston and have won 19 of their past 24.

If the Giants cannot find more ways to score more runs than they have over their past 10 games, they could slide down the standings.

At least the Giants will be well-rested. They were off Thursday after playing 36 games in 38 days and get the four-day All-Star break, plus a day off between their July 22 game in Oakland and the first of their two games in Seattle.

“I can tell you these guys are exhausted,” manager Bruce Bochy said. “Look at the schedule. It’s been a grind. A lot of these guys need a break.”

Posey’s bat: Buster Posey hit a couple of balls hard in the Cubs series aside from his winning double off the right-field wall Sunday, a good sign for the Giants and their hobbled catcher.

Posey said he made an adjustment after assistant hitting coach Rick Schu noticed something amiss.

What was it?

“I can’t tell you that,” Posey said. “I’m in a good place. Hopefully I can keep going.”

Briefly: Madison Bumgarner, Friday night’s starter, has not fared well against the A’s, allowing at least four runs in four of his five starts. The Giants are 3-2. … The Giant are 10-0 with two splits in their past 12 home series. Their only loss in 2018 came in the first homestand, when the Diamondbacks took two of three.

Henry Schulman is a San Francisco Chronicle staff writer. Email: [email protected] Twitter: @hankschulman