I recently managed to link Snowdon, Scafell and the Ben in under 24 hours - using bike and train rather than car. Depart Llanberis: 01.43 (27 May); arrive Glen Nevis: 01:07 (28 May). An entertaining day! A previous attempt with Mick S. was thwarted by a slow running DMU into Crewe, but that's another story.