Keeping in mind to interfere as little as possible with the breast and the baby, letting them just get on with it, breast pads do have their place. When I'm feeding my sons I have a strong flow, so use a muslin square to catch any milk that's flowing before the baby latches on, and if the baby latches off during a feed ( nosy babies always off and on the breast!). Both breasts let-down milk when I'm feeding, so there's usually a wet patch on the breast not being sucked. The let down is only for the first minute or so (as long as there hasn't been too long between feeds), so I insert a breast pad then, and remove it when the flow has stopped. Doing this avoids a wet warm environment around the nipple, which can lead to thrush. I learned this the hard way, getting thrush two or three times while feeding my first son. I was wearing pads all day and night, changing them when they were noticeably damp. This was an ideal breeding ground for the bacteria in the milk, as my nipples were getting no fresh air.
I tried all types of breast pad, pure cotton washable ones - milk just soaks through to your clothes, thick disposable ones - too visible through tops. Then I found slimline plastic-backed ones with an inner that turns to gel when wet, like in a nappy. These are the best I've found, and Boot's do their own brand which work out much cheaper.
I tend to use a muslin for the leaking breast at home, and save the pads for when we're out. If a pad's barely wet after a feed, I'll use it for the next feed. Three months into tandem feeding my milk supply is settling down (elder son feeding less in daytime), so I've less "wasted" milk anyway. It got to the stage when i was just feeding Charlie that we were so in sync there was no extra milk. He'd nuzzle, I'd let-down, he'd feed, that was it. That took about 6-7 months I think. once his major growth spurts had slowed down.