I work with Wor Lass; she's pretty good; but still slow after seven years!
We rarely actually work together; we do our own separate areas and meet up for lunch; and it's a benefit. People always approach her for quotes; rather than me; probably 'cos I'm ugly; in fact the last three (out of four) occassions where we've been 'nabbed' in the street it's been her they've asked.
Another benefit is she disciplines me. Wor Lass likes to know what we're doing the day before, so I'm always organised and we set off at a set time; normally 9.00 am (but I do all the really early stuff by myself and return to pick her up); and if I'm not ready I get a 'thick ear' because of it. She normally works till about 2 or 3 pm, and I drop her off and I go and do some drive-betweens; usually larger jobs that I WFP the lot, rather than 'tops only'.
She's not keen on the cold, but she's supremely fit (she runs at least one marathon a year, countless half marathons and represents East Wales in regional cross-country races) and copes well with the work.
Although not for everyone, it works for us; we actually think we have a stronger relationship because of it; when we're not fighting with each other that is.