Wow I just got the KAB strobe

Glad you like the KAB but take it a step farther, you are not as perfect as you think you are.

You say you say you tweeked it and then played a record. A more accurate way, Put a record on the platter, then put the KAB strobe disk on the record, and your record weight/clamp also. Now your TT motor is pulling a bit more weight and running a bit slower, readjust strobe.

and a bit farther, also place the tonearm on the outer edge of the record, TT motor now has the added drag and weight of the tonearm which will also slow it down, readjust again.
All the exra weight and drag is there and should be considered when setting the TT speed.
PS, keep a spare battery on hand, Murphy`s Law: the battery will fail when you have guests and need to set TT speed.

Wouldn't the addition of the KAB to a record actually put the weight over the intended goal? How close is the strobe disc in weight to that of a basic thinner record? I haven't weighed the KAB so I am just curious as I have thought about doing this also.

Do as Lwerner suggests, specially if you have a VPI with outer ring clamp and spindle clamp - they both add a lot of weight.

I would like to add to this discussion by pointing out that the speed may drift after the TT is switched on and has allowed to warm up and settle in. Let the TT run for about 15 min before adjustments are made.

You can test all these techniques by setting the speed as you have done and with no warm-up. Then, add the record, weights, stylus in groove; and let it warm up. Now check the speed again. Surprise!

I agree with the recommendation of the KAB Strobe. This is a very accurate and easy to use tool.

When using the KAB disc on top of a record is contamination of the record a concern? Do you do this with a record you don't care much about?