Taking Inventory of Your AdMob Ad Units — All the Way to App Open Cooldown Design

Write it into a table

I keep the results in a table, not in my head. I organized it with these columns:

• Unit name (the name in the AdMob console)
• Last few digits of the unit ID
• Type (interstitial / rewarded / App Open / banner)
• Screen used (which Activity or Fragment shows it)
• Frequency control (which setting governs how it appears)

That last column matters most. In my app, interstitial frequency is controlled from the server with action_inters_frequency (how many actions between shows) and action_inters_max (a per-session cap). The rewarded unit uses a combination of reward_period, reward_launch_count, and reward_action_count, looking at both launch count and action count to decide whether to show. Put into a table, it became obvious at a glance that this control logic varied unit by unit.

An App Open ad must not fire on every launch

The thing I most wanted to fix during the inventory was the App Open ad I had bolted on later. Checking the implementation, it showed unconditionally on every cold start. That reliably hurts the experience. Wedge a full-screen ad in front of every open and the users most focused on just launching feel the most friction. AdMob policy also expects a design that lets users pass straight through when the ad has not finished loading.

So I moved to showing it only when three conditions hold:

1. Skip it on the first launch (the very first open after install)
2. A set interval has passed since the last show (I set four hours)
3. The ad has finished loading; if not, show the screen without waiting

The cooldown check is simple: store the last shown time and compare the delta.

class AppOpenManager(private val prefs: SharedPreferences) {
    private val cooldownMillis = 4 * 60 * 60 * 1000L  // 4 hours
 
    fun canShow(): Boolean {
        val isFirstLaunch = prefs.getBoolean("is_first_launch", true)
        if (isFirstLaunch) {
            prefs.edit().putBoolean("is_first_launch", false).apply()
            return false   // skip the first launch
        }
        val last = prefs.getLong("app_open_last_shown", 0L)
        return System.currentTimeMillis() - last >= cooldownMillis
    }
 
    fun markShown() {
        prefs.edit().putLong("app_open_last_shown", System.currentTimeMillis()).apply()
    }
}

On the display side, if canShow() is false I do not even fetch the ad, and even when it is true, I pass through without waiting if the load has not completed.

fun showIfAvailable(activity: Activity, onDone: () -> Unit) {
    if (!manager.canShow() || appOpenAd == null) {
        onDone()           // proceed to the screen without showing an ad
        return
    }
    appOpenAd?.fullScreenContentCallback = object : FullScreenContentCallback() {
        override fun onAdDismissedFullScreenContent() {
            manager.markShown()
            appOpenAd = null
            onDone()
        }
    }
    appOpenAd?.show(activity)
}

The trick is making sure onDone() always runs. Whether or not an ad shows, you guarantee the user ultimately reaches the screen they wanted. Forget this and a failed ad load can stall navigation — the worst kind of bug.

Do not stack ads and review prompts

One more thing the inventory revealed: ad display and the in-app review prompt (governed by review_action_count) could collide in timing. If the review dialog appears right after a full-screen ad closes, it reads to the user as one continuous interruption — "nagged right after an ad" — and tends to drag down ratings. So I separated the counters, triggering the review request on a different action than the one that shows an ad.

Ads are a revenue pillar, but show too many and you erode retention, which ultimately thins out long-term revenue. I always weigh "how much does this one ad lower the odds they open the app again tomorrow?" when setting frequency.

Inventory comes before any revenue play

Before trying a new ad format, accurately grasp what you already have. It is unglamorous, but once you know "which lever moves what," subsequent revenue work gets far easier. For me, this inventory made the next move — the App Open cooldown — surface naturally.

If your ad setup feels like it has grown unwieldy, start with grep "ca-app-pub" before adding a feature. It is astonishing how much it clears your head.