Digital scales

 I rarely weigh each charge, but I always check the weight thrown from my powder measure with the scale, and check perhaps every tenth charge.  The settings on the measure never seems to change, other than when I start on a new jug of powder.  Then, the measure settings change by a few tenths of a grain from the previous jug/lot of powder. 

There are scales that now read in one hundredth of a grain.  I find it hard to believe a scale could be that accurate.  But, I have confidence that the my RCBS scale is within +/- 1/10 of a grain.  It has to be calibrated with the weights provided every time you use it. 

The question “weigh or not to weigh” individual charges is one that will never go away or be resolved.  I think it just depends on how much reloading you do, and if you have confidence in your powder measure or not.  I’ve reloaded enough to gain confidence that it is not necessary for most powders for accurate shooting out to 600 yds.  Some long stick powders (like 3031) will not measure well, so these should be weighed individually.  

But, if you have a scale like the one you have, it could spell big trouble…

Even with the semi-progressive Dillon RL 550 I check weigh frequently. I actually have a fired, with the popped primer still in, case for each caliber, that I dump into to do this. as without that the powder meter fail/safe is a huge pain to cheat.

Also when I set up a "new" charge or batch I not only check weigh 10~12 rounds, but do some double & triple,if the case will take it, loads to get some average readings.

Even with powders like IMR3031 which has the supposedly difficult to meter long sticks are withing ±1/10 Gr.

My old Lyman #55 has a powder knocker built in & a part of the cycle is raise the arm flip the knocker, lower the arm, flip it again.

On the Dillon the Fail/Safe mechanism jars the powder meter as it cycles so its done automatically. The older meters without it don't do that though so it relies on the powder bar snapping back to do a similar job.