The 29-year-old, who was released by Chippa United in January, finally landed himself a deal at the Lions of the North when he signed a six-month deal with the option of another year last week Friday.
"Remember he didn't have a proper pre-season." Brookstone tells KickOff.com. "We took so long because at this club when we do assessment we focus much on the physicality of the player."
Brookstone says the reason Shongwe was offered a short-term contract is because the 2018/19 season is almost finished.
"It's because we're nearly finished the season. He landed his contract and he deserved it. It always takes long, we did the same with Tendai [Ndoro]. We won't sign a player unless we are totally satisfied with him."
Highlands are ninth on the Absa Premiership table with 26 points from 22 games. Their next match is against Baroka FC at Makhulong Stadium on Saturday.