Faster to walk as waiting for the boat or walking to the Skyliner station adds a bit of time. Having said that, especially in the summer heat, the Skyliner is my preferred mode of transportation from Beach Club to Hollywood Studios. Quiet, cool, beautiful bird's eye view of Disney property.
Our last couple Friendship boat rides to/from DHS have been miserably hot as the boat's AC cannot keep up and with no airflow, the humidity is stifling.
Honestly, in all 3 scenarios; walk, boat, Skyliner, you are talking about a few minutes difference. We choose to take the most pleasurable mode which for us is the Skyliner (unless it has a mid-trip hiccup, which in 20+ trips for us has not happened.)