How do you run two WhatsApp accounts on one phone without logging in and out all day?

On most Android phones there is a built in Dual Apps or App Cloning feature (Settings, look for Dual Apps, Clone app, or Second Space depending on the brand). Clone WhatsApp and you get two instances, each signed into a different number. Samsung calls it Dual Messenger. WhatsApp also now supports two accounts inside the official app on newer versions. Tap the arrow next to your name in Settings and Add account. That is the cleanest route if your version has it. iPhone is stricter, no cloning, so people there usually use WhatsApp Business for the second number since you can run Business and regular side by side. On a laptop it is a different story. Most desktop apps only hold one WhatsApp, which is where a multi account inbox helps.

For the phone the clone trick is the answer. Where I kept getting stuck was the computer, because WhatsApp Web only lets you pin one number. I ended up putting both into Spanbox on my desktop so work and personal WhatsApp sit in the same window without logging anything out. Solved the constant switching for me.

WhatsApp Business for the second number. Free, official, runs next to the normal app.