Why is that a problem?
And no, 'a comfortable value is apparently 24 / 4 * 300 = 1800 seconds or 30 minutes', is not a comfortable level, that's a way of calculating the point below which suggests memory pressure, or at least too much churn.
Gail Shaw
Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability