How do you install and check tubeless systems? It´s recommended to put their more of sealant at the initial installation because something is lost during the first sealing..
Then after a while, when you want to check if there is still enough sealant, do you unmount everything, clean it from residues and reinstall? Or you just add new sealant?
In my case, after a while of riding I have realised that my wheels are 150 grams more than they should be..I put the tyres from the wheelset and the added weight was really in the sealant..(30grams were the tyres weighting more than advertised, maybe partly because of sealant residues)..
Now I am really thinking whether to switch to latex..
You shouldn't need to add more than the recommended amount of sealant with most tubeless road tires, especially those with butyl liners. Tires like Compass Bon Jon Pass with their really thin, porous casings might need 10mL more than the recommended amount I guess.
Some sealants come with a dip stick so you can measure the sealant level inside the tire. All you need to do is remove the valve core and stick it down the valve body at 6 o'clock. There is also a system/kit called MilKit
that purports to let you measure remaining sealant by sucking it back up into a syringe. I haven't tried it because honestly my sealant outlasts the tread on the tires I buy. If you store your bike in a cool environment, some sealants like Orange Seal stay liquid for at least 4 months.
As mentioned before, there's really no need to clean/scrub out old sealant. It weighs next to nothing when dried out. Just add more sealant when you stop hearing splashing inside the tire.
Regarding weight...have you actually weighed everything before and after? My wheels almost never come in at advertised weight. There are some very light tubeless tires out there. I have yet to install the Fusion 5 Galactik TLRs, but I weighed both at around 220g. That plus 30mL of sealant is about the weight of the lightest clinchers w/latex tubes. 30mL of sealant will dry to maybe 5g total...it's really inconsequential.