On my 19" monitor set to 1280 x 1024 screen resolution, I can stretch the Layers palette longer to display a maximum of 20 Layers. It could display 40 Layers if I chose the No Thumbnail option (Layers palette menu) and settled for half of the Canvas showing at the bottom, enough to click and highlight.
Here's a screen print with 20 Layers and the Small Thumbnail option:
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