> Do you have problems with time too? How do you cope with that?
I have memorized how time and dates work, but I do not enjoy the system.
Time is my biggest sore point. For starters, doing any kind of arithmetic is an exercise in pain. For example when I rent a shared bike, the system tells me the start and end time to the second - for example, from 13:26:08 to 15:54:39. To calculate the duration, I have to combine the HMS into linear seconds, subtract the two linear timestamps, and then reformat it into HMS notation. Similarly, if I have to calculate ratios, percentages, histograms, etc., then HMS notation just gets in the way.
Have you ever tried writing logic to deal with HMS before? Here's an exercise for you (which I completed this month): Given a non-negative integer number of seconds, write out the number as a string formatted in DHMS format such that the leftmost unit cannot have leading zeros (so no 0m23s, no 09s) except for the special case of 0s, the string must be fully reduced (e.g. 83s -> 1m23s), and any non-leftmost unit must have full leading zeros (e.g. 1h2m3s -> 1h02m03s). The logic is pretty horrendous. The alternative, if everything was expressed in linear seconds, is completely trivial.
The second sore point about time notation is that although sub-second units (ms, μs, ns, etc.) are fine and dandy, any SI super-second unit (kilosecond, megasecond, etc.) is never used in practice and also has no alignment with days and years. This isn't merely a theoretical concern because that's how we get non-SI units like km/h, kW⋅h, and light-year. If ks was useful and popular, then km/ks just simplifies to m/s, whereas km/h = 3.6 m/s and kW⋅h = 3.6 MJ. Personally, I would've preferred the day to be subdivided into either a thousand or a million ticks, especially because I strongly prefer power-of-1000 prefixes (so milli- is good, centi- is bad).
As for dates, we can't get around the fact that there are roughly 365.25 days per tropical year. The Gregorian calendar is hacky because February is shorter than other months, a leap day is put at the end of February instead of the end of December, and the naming is shifted so that Sep (number 7) = 9th month, Oct (number 8) = 10th month, Nov (number 9) = 11th month, Dec (number 10) = 12th month. I think the least bad solution is the https://en.wikipedia.org/wiki/International_Fixed_Calendar .
>> Lots of useless names and numbers to memorize
You are correct to point out that time units have many weird names and conversion factors. Now on top of that, try learning all these names and conversion factors:
• Length: 1 mile = 1760 yards (let's skip furlongs and chains even though they are part of the derivation of the mile), 1 yard = 3 feet, 1 foot = 12 inches. Then there are industry-specific measures like mils in machining, points in typesetting, nautical miles.
• Volume: 1 US gallon = 4 quarts, 1 quart = 2 pints, 1 pint = 2 cups, 1 cup = 8 fluid ounces, 1 fluid ounce = 2 tablespoons, 1 tablespoon = 3 teaspoons. Also, 1 US gallon = 231 cubic inches exact, surprisingly. Throw in some more industry-specific units like cubic feet of water, cubic inches of engine displacement, acre-feet of rain, cubic miles of dirt mined, barrels of oil...
• Mass: 1 short ton = 20 hundredweights, 1 hundredweight = 100 pounds, 1 pound = 16 ounces, 1 ounce = 480 grains; also, 1 stone = 14 pounds (pervasive in UK but nonexistent in US).
• Power: horsepower, BTU/h, ton of cooling, possibly foot-pound-per-second.
The point is, all of the above names and numbers are completely arbitrary and you have to learn them all from scratch. If you aced the test on units of length, that has told you exactly nothing about the units of mass.
It should go without saying in the metric system, the following series mean exactly what you think they mean:
• Length: ... nanometre, micrometre, millimetre, metre, kilometre, megametre, gigametre, ... .
• Volume: ... nanolitre, microlitre, millilitre, litre, kilolitre, megalitre, gigalitre, ... .
• Mass: ... nanogram, microgram, milligram, gram, kilogram, megagram (metric ton / tonne), gigagram, ... .
• Power: ... nanowatt, microwatt, milliwatt, watt, kilowatt, megawatt, gigawatt, ... .
• Frequency: ... nanohertz, microhertz, millhertz, hertz, kilohertz, megahertz, gigahertz, ... .
If you know how many metres are in a kilometre, you know how many hertz are in a kilohertz - you didn't need to learn anything new. You just needed to think for two seconds upon the first time you heard that prefixed unit.
An LED bulb advertised as 2000 lumens (lm) can be easily rewritten as 2 kilolumens (klm) if you wanted to. A power bank marketed as 20000 mA⋅h can at least be simplified to 20 A⋅h (and 72 kilocoulombs if you get rid of the hour).