There are certianly times when you are performing multiple successive
queries where leaving it open makes sense, but leaving them open for with a
minute in between, I don't think that'd justify it.
Expensive has many components too. Leaving 200 connections on a DB is
expensive from your DBA's point of view if it's happening all the time. On
the other hand, it if happens once a day for one minute, then probably not
so much so.
It's really hard to talk about things in absolute terms b/c things like
Network performance and Database performance are often an matter of
trade-offs. A great solution in one instance might be terrible in another.
Think about OLAP for instance, tons of indexes are great for OLAP style
stuff, but you certianly wouldn't want to run google off of a similar
schema.
Perhaps the best way to discern this is to run a trace and see what's going
on?
HTH,
Bill