Like most digital cameras, Leica D-LUX 4 supports Auto Review after every shot. There are five options for Auto Review available in the SETUP menu: "OFF", "1 SEC", "2 SEC", "HOLD", and "ZOOM". By default, it is set to 2 Seconds.
The "HOLD" option allows you to continue viewing the new shot until you press the shutter release or other buttons to get ready for the next shot. This is good for serious photographers who may spend a bit more time to evaluate each shot and make changes accordingly. I had used this option for a while and found it was quite convenient.
But I recently found an issue of Auto Review which caused me to disable this feature at all.
The issue is: while Auto Review is working on HOLD, the aperture is on hold, too. That means, the lens does not return to full open aperture after shutter fired until Auto Review stops showing the last shot. The issue also applies to the other options of Auto Review, of course, except the "OFF" one, though the duration is less than 2 seconds with these options.
This is really not good for the lens, one of the most expensive parts of the camera. The aperture of this lens should be better at the wide open position while not at work. The aperture is fully opened when the camera is power off.
As it is not necessary to keep the aperture working while reviewing a photograph because the shooting procedure has finished, I speculate this is a defect of D-LUX 4 firmware, which is inherent from the LUMIX firmware of Panasonic DMC-LX3.
However, the conclusion is just to turn OFF the Auto Review, at all.
Simply pressing the "▼/Fn" button* lets you review the last shot instantly, even for a long time with no worries about the aperture as it is no longer working in this stage. There is one more advantage after disabling the Auto Review, you may continue to shoot without any pause, if required, therefore you won't lose any chance to capture a decisive moment.
* The "▼/Fn" button can be customised for other purposes. Make sure the "Fn BUTTON SET" option in SETUP menu has been assigned to "REVIEW" (the default setting) before disabling the Auto Review.