Why update the same time? What I want to ask is usually android app not update but in someday those will have a tons of update and I can ensure that it is not my phone problem. So why apps usually update the same time ? Any reasonal explain for this ?
If I am interpreting your question properly, you are basically asking why sometimes you see many apps update all at once.

The answer is simple: it is more efficient to update many apps at once.

In Android, especially in Android N+, emphasis is placed on network and CPU performance and optimization when running tasks.

When a developer wants to run a background task, they can create a job and register it with the Android system to run under certain conditions.  This creates a convenient way to run tasks in a batch, thus being more device resource friendly.  Jobs that are enqueued by the system can kick off and run based on device conditions/properties, like: "when the device is charging" or "when the device is on an unmetered network".

Google Play, for example, queues up app updates when the device is on Wi-Fi networks or while plugged in.  You can change the behavior of app updates in Settings.  



This is why you will often see many apps update after plugging in your device or hopping onto you home Wi-Fi network.