Generally, users are signed-in forever on native apps (unless uninstalled or moving to a new phone), but there's a legacy of having timed out sessions on web (i.e., sessions expiring after 10 minutes on most banking or travel sites, slightly longer on other websites).
To better understand this behavior, we've created a quick 5 minute survey here for our Google Identity team to learn about your web stack & practices around session management. This will help guide us in recommendations around our Credential Management API for seamless sign-in that was announced at I/O.