The phrase "a practice that sometimes" is correct and usable in written English.
It can be used when discussing a specific practice or behavior that occurs on occasion or under certain circumstances.
Example: "A practice that sometimes leads to misunderstandings is the lack of clear communication among team members."
Alternatives: "a habit that occasionally" or "a method that at times".
In some cases, the miners shoot water from high-powered hoses to break up the rock walls, a dangerous practice that sometimes triggers landslides.
Richo's books emphasize love as an ongoing practice that sometimes fails.
The regulations also tighten the prohibition against paying recruiters by the number of students they enroll — a practice that has sometimes led to boiler-room call centers that pressure those with little chance of academic success to enroll.
Many migrants arriving in Italy refuse to give their details, hoping to travel on to northern Europe to request asylum, a practice that is sometimes tacitly encouraged by Italian officials.
We're also told that some investors were initially concerned that co-founder and CEO Katrina Lake had planned to sell shares at the time of the IPO, a practice that is sometimes construed as a signal that insiders are less than confident about a company's longer-term performance.
Carla Gugino plays Cathy Rush, a first-time coach (now in the Basketball Hall of Fame) who takes over a doormat team and, with relentless practices that sometimes border on abusive, shows its players how to win.
Iran's business climate also poses formidable challenges, including a byzantine regulatory system and unorthodox accounting practices that sometimes have left companies wondering whether they will be able to repatriate any profits.
Critics say the fraternity system leads to drinking, hazing and other dangerous practices that sometimes result in death.
During the Middle Ages a great many pieces of furniture, including those with carved decoration, were painted and sometimes gilded, a practice that continued well on into the Renaissance (the present state of existing pieces, with their plain wooden surfaces, is misleading).
The agencies sometimes were allowed access to confidential corporate information, a practice that should be banned.
