The term working weight refers to the weight you are using for the majority of your sets, this should be a weight that challenges you, but is also manageable.
This weight will likely be different depending on the exercise, for instance the kettlebell you use for squats should be heavier than what you can press overhead and the bell you use on the get up should be heavier than the bell you can strict press.
Although you should spend time with your working weight, you should also frequently drop to the bell below for easier workouts focusing on technique and occasionally you should challenge your self and pick up the bell above your working weight for some heavy low repetition work.
The saying “if you always do what you’ve always done, you’ll get what you’ve always got” is appropriate at this point.
Meaning, you should always be striving to push forward and challenge your self, albeit in a manner that has you waving the loads from light to heavy throughout the course of your workouts.
The most optimal way to make progress in any type of physical training is to take a light/medium/heavy approach, this can refer to the weight, intensity or volume.
The above example refers to weight, if my working weight is a 24kg bell, I am going to have a light workout with a 20kg bell, then a medium workout with the 24kg, the next workout I will push myself and try to get some reps with the 28kg, then I will start over with an easy workout using the 20kg, then progress back up to the 24kg and so on and so forth.
This method has you working with your physiology and allows for adaption to occur at a steady pace. After all, making adaptions is essentially what we are striving to do in our training, and this method works regardless of whether we are trying to make strength, power or endurance, adaptions.
So figure out for each lift that you do, what is my light weight, what is my working weight, and then of course you will know what is your heavy weight. Spend time rotating between these three bells in successive workouts. You will find that your working weight will start to feel light if you can train consistently using this approach for several weeks.
If you are new to weight training, then this rule does not apply so much until you are past what we call newbie gains. Anyone who is new to weight training will gain and build strength rapidly, as long as you have dialed in technique and put forth consistent effort. You are likely to progress up a couple of bell sizes within your first 8 weeks of training. When you get to a weight that you find very challenging, start to use the above points and wave the load. Then figure out your light, medium and heavy weight for each lift.
It also must be said, that once you get up to a challenging working weight, you must have adequate warm up sets to get up to using that working weight. For example, if my working weight is the 24kg, I might do a progressive warm up set with the 16kg, then with the 20kg, and then get onto the 24kg for my working sets. If I am at a stage in my training where I am using very heavy weight, I will spend more time on progressively warming up.
I hope that points have been useful, take them on board and you should start to see better progress in your training.