I found 2L diffusers on Amazon and I love them! They run for like a full day.
Pure Enrichment PureSpa XL - 2L Ultrasonic Cool Mist Humidifier + Essential Oil Diffuser, Powerful Mist Coverage Up to 350 sq ft for 50 Hrs, Soft Color-Changing Lights and Quiet Operation https://www.amazon.com/dp/B0774X5PTV/ref=cm_sw_r_apan_glt_i_SCPKM281H18FBSRY1ZXF?_encoding=UTF8&psc=1
I got this Pure Humidifier from TJ Maxx, but here’s the Amazon link. It lasts almost all day - or most of the work day - since my apartment is also very dry. It gets the air around my plants to about 50-60% humidity, and my plants seem to like it.
... also it changes colors. Not gonna lie; that was half the reason I got it lol
I don’t have a super fancy humidifier. I went to TJ Maxx and got the biggest spa humidifier/diffuser I could find. On High, it will runs for for about 12-15hrs; and Low for about 20hrs. I’m pretty pleased with it. It also changes colors haha. I don’t own this specific one I’ve linked, but I have the smaller one of this brand.