It's fine as long as bike paths are physically separated from cars and are maintained to the same standard as roads. My college had a network of pedestrian/bike paths that they plowed in the winter, and I and many others had no problem biking year-round.
Here's Seattle's network of protected bike lanes: <https://i.imgur.com/vEDhqoz.png>. Note that many of them are flawed in one or more ways:
* There are frequent car crossings at blind alleys and driveways, often every 20-30 feet.
* Many are "protected" by flexible posts that are easily driven over.
* When protected bike lanes run next to roads, drivers often turn across them at intersections without looking.
I generated the map with Overpass Turbo: <https://overpass-turbo.eu/s/1mT6>. To make it render nicely, check "Don't display small features as POIs" under settings. If you want to try it for a different city, drag/zoom it into view and hit "Run".
I used to ride as far to the right as possible on roads without bike lanes, but then I got hit by a driver trying to squeeze past me without changing lanes.
