Porto Santo would be used for a quick 'splash and dash' rather than a night stop. The benefit of Porto Santo is that it's close. Compared to Faro you'll get another hour and a half of holding fuel. So if the weather is marginal at Funchal you're better off holding for as long as possible, ping into PXO, have another go at FNC then clear of to the Canaries. But, it's only got 7 stands available and it fills up quickly so that isn't always possible.