边走边工作：一套不会掉链子的上网组合

It depends which risk worries you more. If your fear is running out, one larger plan is simpler to manage and usually better value per gigabyte. If your fear is having no usable connection at all somewhere, two plans on different networks give you an option a single large plan cannot. For people whose income depends on being online, we generally suggest a primary sized properly plus a small second one as an escape route.

It may be, but read the terms first. Almost every plan described as unlimited defines a full-speed threshold and reduces speed beyond it. What remains after that reduction is often fine for messaging and email, but not necessarily for a video call with the camera on. Those terms vary by plan and country, so check the specific plan page.

Sharing itself adds nothing, but a laptop naturally uses more: it loads full desktop pages, syncs files automatically and downloads large system updates. The effective fix is to mark that connection as metered in the laptop's operating system and postpone heavy tasks until you are on Wi-Fi.

If a backup profile is already installed, switch to it; that takes under a minute. If it is not, finding usable Wi-Fi comes first, because buying and installing a new profile needs internet regardless. Meanwhile, tell the other participants through whatever channel still works, even a plain text message.

For a solo worker whose phone can share its connection, usually not: you get much the same result without another device to carry and charge. If you need several devices connected all day, or you work as a team sharing one connection, a separate device keeps the phone's battery out of the equation. Both approaches involve trade-offs, and there is no single right answer.

Yes while on mobile data, then re-enable on Wi-Fi, so background sync does not silently drain the plan.

It can be, provided you accept the full-speed cap, because nearly every unlimited plan throttles after a stated threshold.