1. How do you know what intensity to lift in order to get stronger? 
2. Do you keep track of your total lifting poundage on a weekly basis? 
3. How do you know how much total work volume you’re putting in for your strength training? 
4. How do you calculate true strength gains? 

If you’re looking to keep a measure on making some real gains in strength then you MUST understand how to measure it. To do this you need to understand how to calculate your absolute work volume.