Set defaut period for average block time counter refresh interval

CHANGELOG.md

@@ -14,6 +14,7 @@
 - [#3564](https://github.com/poanetwork/blockscout/pull/3564) - Staking welcome message
 
 ### Fixes
+- [#3730](https://github.com/poanetwork/blockscout/pull/3730) - Set default period for average block time counter refresh interval
 - [#3729](https://github.com/poanetwork/blockscout/pull/3729) - Token on-demand balance fetcher: handle nil balance
 - [#3728](https://github.com/poanetwork/blockscout/pull/3728) - Coinprice api endpoint: handle nil rates
 - [#3723](https://github.com/poanetwork/blockscout/pull/3723) - Fix losing digits at value conversion back from WEI

apps/explorer/config/config.exs

@@ -23,7 +23,9 @@ config :explorer,
       else: Explorer.Chain.Events.DBSender
     )
 
-config :explorer, Explorer.Counters.AverageBlockTime, enabled: true
+config :explorer, Explorer.Counters.AverageBlockTime,
+  enabled: true,
+  period: :timer.minutes(10)
 
 config :explorer, Explorer.Chain.Events.Listener,
   enabled: