Once you start to work with layers, you won’t want to go without them when processing your images. Sometimes, however, the number of layers in an image can get out of hand. There are various Photoshop options available to help you keep your layer processes manageable:
Thumbnail size options
Layer naming (the more descriptive, the better)
Linking and grouping layers
Merging and flattening layers
The Layers Panel Options menu at the top of the panel contains options for adjusting the layer entry thumbnail size and various other display parameters.
The more layers your image has, the smaller you need to set your thumbnails ...