I have no Lear -40/-45 experience, but in the -30 series the L/R BLEED AIR switches are not normally ever closed by the crew, including during start or shutdown, but the CABIN AIR is turned on prior to takeoff and closed after landing. In the -30 series aircraft, the BLEED AIR SHUTOFF VALVES (SOV) are spring-loaded open and require DC power to close them.
My procedure (and SOP in various companies for whom I've operated) in the 30 series Lears has always been to shut off the bleeds prior to engine shutdown, and to open them after start up.