This was the case about 30 years ago but not with current systems unless you get the really cheap stuff. Almost all dyno systems sold today and for the past 20 or 30 years are 'stand lights' which means they stay on while you're standing still.

We've dyno systems on all of our daily use bikes. Some are hub dyno's and some are bottle dyno's. Lights are B&M, Spanninga, and Schmidt. All work quite well (and we do a lot of riding at night going to/from dinner and grocery).

Two good sources: https://www.dutchbikebits.com/lights and http://www.peterwhitecycles.com/lightingsystems.htm

Be careful about relying on Lumens. A light with low lumens but good optics can be much better than one with 4x as many lumens but poor optics. 100 lumens where you want it is much better than 400 lumens scattered all over. A better measure is Lux which gives you an idea of how much light there is on any surface area, but that's another topic...

Be careful how you aim your lights. Blinding or annoying drivers, other riders, or people walking is a really bad idea.

Fortunately the 'I have to have gobs of flashing lights all over or I'll get killed' bit seems to have died. The overwhelming majority of folks don't flash anymore. Flashing lights are annoying and can cause some drivers to drive in to you instead of seeing you and avoiding you. I think the U.S. is the only developed country that hasn't outlawed them.