I routinely download stuff overnight, or when I'm out during the day. Sometimes downloads take several days, though I do pause the download when the Internet is needed for other purposes. GOG and the Humble Bundles don't require any sort of check-in. You don't need an internet connection to install, activate, or run their software. Heck, you don't even need your own internet connection to download it since everything can be done through a web browser (no special software required).

Of course GOG means you're stuck with (often quite old) games and Humble Bundles means you're (usually) stuck with indie software. So you're not going to get the latest and most popular releases. Yet it's perfectly fine if you like the fare.