Each person and situation is different.
There are some people who do commuting and errands averaging 1 mile each way.
Others do 20+ miles each way.

My average commute/errand run is about 20 miles RT, and often reaches 40 or 50 RT. I've had "fun rides" over 100 miles, and my longest trailer pull was about 100 miles RT picking up some Craigslist bike frames in a nearby city.

I've probably had my cargo bike + trailer out for more 40 mile RT days than 20 mile RT days. However, I would just not do the ride on an MTB weighing 50 lbs... just wouldn't do it, and it wouldn't be fun.

As far as lights that I've used, they've varied over the years, and how much I expect to be riding during the daylight vs after dark. I bought my Night Sun lights for a 10 mile graveyard/swing shift commute. They eventually came off when I started doing mostly daylight riding, and perhaps got replaced by blinkies (be seen, but not enough to illuminate the road). One of my worst "wrecks" was at dusk using blinkies on an unfamiliar road where I let my wheels fall into road cracks, doing a number on the rims, and jamming up the elbows quite a bit.

I'm now hitting more after dark riding on rural roads with no overhead lighting, and it is time for good bright lights again.

Anyway, each person is different with different riding goals, and there is no one-size-size-fits-all. I wouldn't overspend on a commuter, but I'm happy that I commuted on my Colnago for many years, to the point where it shows significant wear.