Culling in LR can be very efficient if you have a couple of macros and two monitors. I often have 300-1000 file almost daily to cull. Here is what works for me. I am not putting down the FastRawViewer program. For some it may be the way to go. For others, the method shown below may suffice.
Main monitor in Grid mode, secondary monitor in Loupe and set to Live. Select first file, press macro. Files have no color assigned. Six files are selected and (important) set to color red and and put in Survey on the main monitor. The selected file shows full screen on the second monitor. If focus is an issue and you wish to check it do the following: set second monitor to 100%. As you move the cursor over the files in the main monitor, the second monitor will show the area under the cursor. So you can quickly move the cursor to the area of each file that you want to be in focus and see the result in the second monitor. The X key will reject the file and remove it from the Survey. Ctrl + click on a file (main monitor) will remove it from the Survey but keep it as selected. So when checking focus, if no good then X. If good and you really like it and want to keep it then Ctrl + click (on main monitor). Otherwise just leave the file in the Survey for comparison with other files. Often the Survey files are large enough so that you can determine if it is a keeper or not. If you really want to check it out, click on the Second monitor image area to set it to Fit. Now you can see each file full size by simply moving the cursor over each file.
There are many schemes that can be used when using the X key and Ctrl + click. The method I use most often is to put into Survey mode, check focus is required, reject the out of focus, and Ctl + click the definite keepers. Analyze the remaining files in the Survey and Ctl + click to good ones. Any file that remains in the Survey is to be rejected. Switch the main monitor to Grid mode and press X to delete the highlighted files which are the file you wanted to reject by leaving them in the Survey. The good files have been tucked away with Ctl + click.
At this point you are in Grid on the main monitor. Select the fist non red file, press the macro key again, and repeat. The files are colored red so you can keep track of where you are at, what you have done and what you have to do.
As i said, there are other ways to select and reject. Use any method that suits you but be sure you are keeping the selected files and rejecting the unwanteds. For example, instead of Ctl + clicking the good files and the deleting the files that remain in Survey, you can reject all the bad files, leaving the good files in Survey. In this case DO NOT REJECT the files when you go back to Grid. Just keep in mind how you have selected when you come to the Grid operation. I use both methods and have no problem keeping it straight. You might initially get confused but with a little use the confusion diminishes. If all the Survey files are crap, I delete at the Grid operation. If they are all great, I keep at the Grid operation. In between, depends on how I feel.
It goes pretty quick. I usually make two passes. For the second pass I first set all the files to no color so it works the same as the first pass. I am usually working an event with many files so I may have taken an image, done something else, and returned to the first image situation. So I may end up with two files which are very similar but separated in time so in the first culling pass so I can't compare them. The second pass will usually have these files close together so the fall in the same survey. If they don't fall in the same survey, I manually select the files in question and press N to set them in Survey where I can make the selection. I want to get the number files down in count because I often have to run a denoising program and more files takes more time.
The macro is a simple macro used in a keypad such as Genovation CP24 ($85 - $100 but does a lot more that shown here, ad follows). I put keys that even though they are accessible on the keyboard on the keypad for the following reasons. The keypad is directly under my left hand and the left arm is resting on the chair arm. All keys on the keypad can be accessed by not moving my hand or arm. Keys that have a relationship to each other are close together, for example, develop and grid are next to each other. I find combinations key sets awkward and sometimes a long finger stretch. The keypad puts it into one key. I keep my right hand on the mouse (ex tablet user) so it is not generally used for keystrokes. This means that the left arm has to move across my body to get to keys on the right side of the keyboard. I don't like that. Face it, I am lazy and want to move my hands and arms a little as possible and I am at often for six or eight hours. By the way, you can label the keys so you know which macro it invokes. You can use any keypad you like but be sure it has this feature.
To be able to call a command from the keypad and make a macro it must have a hotkey assigned to it. If no hot key is assigned to the command then you must create one using a program such as AutoHotKey. That is another story. But that said, there are many useful macros that you can make even with this restriction.
I have many useful macros. For example I have a finished macro. It gives the file two stars, copies the settings, and moves to the next file. So when done with a file I press this key, am at the next file, and if similar I press another key on the keypad which pastes the settings.
The macro used here follows:
You start with the first file selected, the macro selects the next five files keeping them highlighted. The the number 6 is invoked to change the color to red and P used to show them picked. Finally, N is pressed to go to Survey. I cluster the keys that are used together in a close pattern on the key pad. I have the X key for reject, the macro key, the G key for grid, and the Ctrl key close to each other in a convenient place on the pad.
I use six files. You can use more or less if you like. Six gives me large enough Survey images for comparison on my monitor. Your set up may require a different amount.