With insurance companies often paying doctors less for their services and with paperwork increasing, Dr. Gregory Yu was putting in longer workdays to squeeze in more patients. He figured there had to be a better way. So a few years ago he shifted a portion of his practice to a concierge model in which patients pay a monthly fee of $150 in exchange for more of his time — both in and out of the office. "It was more for my own personal longevity," said the La Cañada Flintridge internist, explaining why he made the switch. "