How do I set DataAdapter.UpdateBatchSize to a "optimal" value?

Question

Hi there,

I've finally gotten my insert batch to work and now I've been fiddling with the size of the batch, but I can't see any difference in performance between a value of 50 and a value of 10000. This seems very odd to me, but I don't know what's happening behind the scene, so it might be normal behavior.

I'm inserting 160k rows into a table and the mean time for my tested values is 115 +/- 2 secs. Without batching it takes 210 secs, so I'm quite satisfied with the improvement. The target table is:

CREATE TABLE [dbo].[p_DataIdeas](
    [wave] [int] NOT NULL,
    [idnumber] [int] NOT NULL,
    [ideaID] [int] NOT NULL,
    [haveSeen] [bit] NOT NULL CONSTRAINT [DF_p_DataIdeas_haveSeen]  DEFAULT ((0)),
  CONSTRAINT [PK_p_DataIdeas] PRIMARY KEY CLUSTERED 
(
  [wave] ASC,
  [idnumber] ASC,
  [ideaID] ASC
)WITH (PAD_INDEX  = OFF, STATISTICS_NORECOMPUTE  = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS  = ON, ALLOW_PAGE_LOCKS  = ON
) ON [PRIMARY]

) ON [PRIMARY]

I read What to look for when setting UpdateBatchSize and the answer was to simply test a couple of different values. I can understand that, but shouldn't it be possible to calculate or at least guesstimate a good value if you know the table design, the SQL question and the data that's about to be inserted?

Are there any best practices out there that someone can recommend?