WASHINGTON — During his transition from Florida governor to likely presidential candidate, Jeb Bush served on the boards or as an adviser to at least 15 companies and nonprofits, a dizzying array of corporate connections that earned him millions of dollars and occasional headaches.

Bush returned to corporate America after leaving the governor’s mansion in early 2007, and his industry portfolio expanded steadily until he began shedding ties late last year to prepare a run for president.

Executives who worked alongside Bush describe him as an engaged adviser with an eye on detail.

Yet experts question how anyone could serve so many boards at once effectively.

“Board of directors and advisory boards are in charge of high-level oversight,” said law professor Elizabeth Nowicki, a former Securities and Exchange Commission lawyer. “You cannot possibly do that simultaneously for 10 or 15 entities.”