diff --git a/main.py b/main.py
index 32459ee..4d8ab29 100644
--- a/main.py
+++ b/main.py
@@ -14,6 +14,7 @@ MINUTE_MS = 60000
 HOUR_MS = 60 * MINUTE_MS
 LOOKBACK_MS = 60 * 24 * HOUR_MS
 MATCH_MS = 2 * MINUTE_MS
+MINUTE_RESOLUTION_LIMIT_MS = 7 * 24 * HOUR_MS
 EXIT_RETRYABLE = 1
 EXIT_PERMANENT = 2
 REFUSED_STATUS_MIN = 400
@@ -156,14 +157,18 @@ def mean_max(series, start_ms, end_ms):
 
 
 def coverage(series, start_ms, end_ms):
-    total = max(1, (end_ms - start_ms) // MINUTE_MS)
+    total = max(1, (end_ms - start_ms) // series["stepMs"])
     present = sum(1 for t, _ in samples(series) if start_ms <= t < end_ms)
     return min(1.0, present / total)
 
 
+def pick_resolution(duration_ms):
+    return "1min" if duration_ms <= MINUTE_RESOLUTION_LIMIT_MS else "1hr"
+
+
 def build_row(host, start_ms, end_ms):
     cpu, ram, disk = f"{host}-cpu", f"{host}-ram", f"{host}-disk"
-    history = read_history([cpu, ram, disk], start_ms, end_ms, "1min")
+    history = read_history([cpu, ram, disk], start_ms, end_ms, pick_resolution(end_ms - start_ms))
     row = {"start_time": start_ms, "end_time": end_ms, "duration_s": (end_ms - start_ms) // 1000}
     for prefix, signal in (("cpu", cpu), ("ram", ram), ("disk", disk)):
         row[f"{prefix}_mean"], row[f"{prefix}_max"] = mean_max(history[signal], start_ms, end_ms)