My understanding of the definition is that it originated in America and was for very long series intended to be completed by car. There’s quite a lot of info, videos etc. Every 0.1m there is a cache on the guardrail. Drive, jump out, sign, jump in.
Over 1,000 caches in a day have been achieved by teams working together, taking turns to jump out and sign. In some cases, not even sign, just slap a sticker on the outside of the cache, sometimes without even getting out of the car! Averaging one minute PER CACHE, including travelling.
Each to their own, but that doesn’t sound like fun to me, and why I dislike the term “Power trail” when applied to a walking series or series, even if the density is the same.