It's not for pastry this time, it was for crumble (which I didn't say, so you are excused for assuming it was pastry!). I've used the FP in the past as that way you can use cold butter and still get fine crumbs but my FP is a pain to get out and wash/clean so wanted to use Mr Mixer instead.
In fact I don't make pastry very often (and only ever make shortcrust, I know about the butter lumps and air pockets for flaky but I never make it, none of us are big fans), but was taught at school how to rub in, which was to a fine crumb and it has always served me well for pastry, scones, biscuits and crumbles. I finished it off by hand today, maybe next time I will leave it lumpy and see how it cooks, obv doesn't matter with crumble but for pastry I can't believe it won't leave greasy / dry patches. Thank you for thinking about it for me!