>>576actual gamedev here, this is pretty much the opposite of true
generally you want to squish every single one of your textures into as few giant files as you can (texture atlases) to save VRAM, since ideally all your texture files will be POT or Power of Two (128x128, 1024x256, 512x512) etc in order to be supported in hardware by as many graphics card configurations as possible. since it's very likely that you won't manage to perfectly fill up a POT texture
BUT speaking pratically this general attitude isnt 100% applicable to 2D rpgs because 1. texture atlasing isnt as big of a concern since square tiles pack perfectly with no wasted space and 2. it's 2016 your sprite game isn't going to go past 10% CPU utilization even if you render everything in software unless you actively try to write the shittiest engine possible like the LISA guy apparently did
anyway a 2048x2048 texture is like 16 MB in VRAM and modern cards have 4GB plus so I guarantee all the pixel art you could make in a lifetime will fit and you aren't going to have loading times as long as you don't do something stupid like save everything as a TGA instead of PNGs
splitting tilesheets into themed areas for organization is a good idea though
