I use about 8 gallons a week on a 24"x24" tank.
While the wife's jbj with 150 halide is 2/3 liters a week. But it's covered

I'm expecting my volume to double as this week I'm putting halide back on my tank

approx. 1.5 g per day 90 g tank with a 50 g sump glass covered DT tank

On my 150g tank I go through roughly 8-10g every 5 days. Evaporation is normal, but there are people who dislike it and try very hard to reduce or minimize it. I on the other hand welcome the evaporation and try to use it to my advantage. That is, I use evaporation as a means to help keep my tank cool. I have a completely open display tank with fans that blow across the surface of my water to increase evaporation when the tank gets hot during the mid day.

Auto-top off systems are your friend. If you're manually adding top up water that does get annoying fast. Get a reservoir to hold your top up water and buy an auto-top up system. There are lots of them on the market.

I have a 20 gallon garbage can for my ATO I fill that up once a month for my 95 gallon tank

I have an ato with a 5 gallon water container. The 5 gallon lasts me between 7-10 days on a 90 gallon with 30 gallon sump. DT is covered. Winter air is usually a little drier so I'm not sure how many gallons I'll go through in the coming months. I might bump my ato up to 10g for convenience.

Back when I had my 2 90s, I had a reservoir of about 15 to 20 gals plastic bin, I had to top it off every 3 to 4 days, that got annoying very fast like someone said it here. On my new 260G build, I went completely automated, now I have a floating arm that connected straight into my water filter. I just do a bit of maintenance every month or so and I forget about it.

144G display
55G sump
55G frag tank/refuge
Approximetely 5g is pumped from reservoir

120g + 40g sump @ 1.5-2g per day running Leds

60 gallon display, 15 gallon sump, I use about 3 gallons a week in the summer and double that in the winter (ATO from resevoir).