Actually I was quite surprised at how well it held on poorly dressed timber... however, it did need to be "dressed". The wenge I suspended with it was very coarse... I have even managed to hold some resaw cuts off the bandsaw... though that was just a POC... I would normally joint it before clamping with the VAC-SYS.
If your first cut is too short... Take the second cut from the longer end... LBD