Sorry if I'm stating the bloomin' obvious, but I've found that the type of floor covering (or none) that I'm pressing up from can give you a slight edge or not. I find carpets are to be avoided as there's too much slippage. Lino floors are OK if my hamds are a bit moist, say from washing them, but the best in my house are the slightly riven flag floors. They're good for a couple extra reps at least or a few more seconds of 'Sallying forth'