"A 10-watt laser will appear much brighter than a 10-watt light bulb since the light from the bulb travels in all directions and spreads rapidly, while the light from the laser is concentrated in a beam only a few millimeters in diameter." ~ www.laserFX.com
Here's a helpful way to think of what happens when we narrow the focus of our story:
Let's say you have decided not to write a memoir that is book-length. Let's say that's somewhere in the order of 300 pages. Now, let's call these pages 'watts'.
You already know where I'm going with this, but I'm going to continue anyway, as the point cannot be made too strongly. Obviously, you have a choice as to how you are going to use those 300 watts. You could use them to light up a large area--every trip you've ever taken--in which case that light will need to be diffuse in order to illuminate such a wide swath of time and cover so many subjects. It will illuminate a broad area, but it will be difficult for that light to penetrate any one area in an intense or profound way. It can't; the energy of the light is being focussed laterally. Which is fine, if that's what you want. If the work you are looking to write is a list of entertaining highlights from all the places you've ever been, then that's what you're going to get. If you want a memoir, however, a work that probes deeply into both the place and your experience of it, that moves, transports and transforms the reader, then what you will probably need is a more focussed, penetrative light. You need a laser.
Paradoxically (again: art is full of paradox), this narrowing of focus in no way limits you from exploring the full breadth of your experience. You may well find yourself drawing on experiences you have had over the course of all of your travels and channeling that knowledge into your presentation and understanding of just one place, for example. Which isn't to say that we cannot write about multiple places, multiple experiences, wide swaths of time. But we need to have a focus for those experiences. There needs to be a reason, a theme, a connection, a resonance that draws these myriad experiences together into a coherent whole. It is another way of focussing that light.
Maybe you were a doctor with Medecins Sans Frontieres and worked in twelve different countries, all of them fascinating, all of them soulful experiences. Readers would be able to move through all twelve of those situations with you if we were to feel that they speak to each other in some way, if they form part of a larger journey, perhaps, an evolution in your understanding of aid, of volunteering, of how you see yourself or your work or the presence of grace and kindness in a world that seems only to report the opposite. Whatever it might be. But to include every great adventure for the simple sake of being able to include every great adventure may well leave the reader unsatisfied. If all they ever do is wander around looking at things, they might just as soon have picked up a guidebook.
The best travel writing takes us to the heart of its subject and transforms a reader's understanding of it. So does all the best writing.