Plus it depents on how much aquascaping you want to do.
If it's just a few plants and a few minutes, I would leave the fishes in there, since putting them in a bucket is a little stress, too.
But in case you want to replant the whole aquarium and it might take you half an hour or an hour or so, I would maybe put them in a bucket. If you redo the whole landscape there will probably also be a lot of dirty, cloudy water, from the gravel. I would wait then until it's settled a little bit, before putting the fishes back in.
Previously: 2x 10gal tank, 45gal aquascaped, 70gal aquascaped
Currently: 16gal FW, 40W CF, ADA Aquasoil Amazonia II/Tahitan Moon Sand, PH 6.5, kH2, gH 4