A travel kit for all your travel supplies (from toiletries to snacks as well as locks, adaptors, chargers, etc) saves you a lot of time in preparing for a journey. Travel supplies also include accessible holders for important documents and IDs.
This saves you from forgetting something on your list because these things never leave your kit and will always be handy wherever you go. Of course, once in a while, you have to make sure that your flashlight bulb and batteries are ready for use otherwise they would require some changing.
When buying or finding yourself a kit for these essentials, consider what goes together, which can come in individual packs, which can be left behind depending on your destination, which can accomodate the things you really need, no more, no less (because a loose bag might make you think you don't really need anything there and before you know it, you've just left behind your aspirator or something). And always leave these things inside your luggage, preferably in one kit (or for packing purposes, in containers at least).
You can choose to get a complete and matching set and just tag them properly, or you can use color-coded/design-coded containers (like a billfold in shocking pink which you can easily spot in a jumble).
For an added incentive, having an established travel kit will ive you more time to plan your wardrobe or revisit your itinerary.