Yes, I did, both before BSc, and between BSc and PhD (2 there in fact). Don't know if it's helped as haven't started PhD yet, but I think it helped with BSc. I guess it depends how you spend it...
I took a year off between my Master's and PhD, when I was offered position through the University where I currently study. The experience really helped decide if I wanted to do a PhD, and allowed me to decide if I could work well with my current advisor.
I worked for 3 years (lab tech) between undergrad and PhD. I think spending some time before embarking on a PhD can be very beneficial, especially if you can spend the time gaining relevant experience. Good luck.
It is useful to take a gap if you are not 100% sure if you should be doing a PhD in the area. You might find you enjoy having a proper job (with lots of money).
It took me time to get my PhD place sorted when I finished my masters, so I took an unplanned 9 months out doing an awful job, which I hated for every minute. But I think that it has made me more motivated in my PhD as it's something I never want to go back to