Relying on a single backup method is risky; combining iCloud backup with an occasional local backup through Finder or Time Machine covers both convenience and a full offline copy.
Automatic iCloud backups run overnight while the device charges and connects to Wi-Fi, which is easy to overlook if that routine is disrupted while traveling.
Testing a backup occasionally, by checking that recent photos and documents appear correctly, is the only way to be confident a backup will actually work when it’s needed.