As previously mentioned, there are several reasons, both practical and aesthetic, why preparing a nice and neat cap will be helpful.
One reason is that your application of choice may in fact depend on a specific arrangement of the actiCAP electrode leadwires. For example, in TMS-EEG studies, the orientation of electrode cables relative to the stimulation coil has an impact on TMS artifacts picked up in the EEG signal, so you may want to route the leadwires in the direction that minimizes these artifacts (Sekiguchi et al, 2009). In ecologically valid and mobile investigations, you may instead want to stabilize the leadwires to reduce artifacts caused by free body movements. Furthermore, if you would like to perform source localization and are using the CapTrak to detect the exact locations of the electrodes on the scalp, you would aim for a tidy cable arrangement so that all the LEDs in the electrode housings are not concealed by overlapping or messy leadwire spaghetti and can be correctly detected by the scanning system.
Tidy preparation of an actiCAP snap cap will also help you to minimise set up time because you will not need to fiddle with lots of loose electrode leadwires. For example, if you are running a cognitive study with visual stimuli presented on a screen, you would aim to keep leadwires out of the field of vision, thus more towards the back and over the shoulders of the participants. A cap that has been prepared following this fashion from the beginning will only need to be put on the head of the participant and impedance checking can start immediately with no additional fuss. This will also make removing electrodes for cleaning much faster.
Being mindful of how you are setting up your actiCAP cap will also help you take good care of it in the long run. Preparing the cap in a way that electrode leadwires do not cross each other too much will prevent unintentional damages and ensure longevity of the equipment.
Finally, having neatly arranged cables with a minimum of cable spaghetti will be much more pleasing to look at, adding to the professional appearance of your lab!