I do do same - plant 1 to 8, then remove 1 (cheapest seed) and re-plant it. It's slightly better than what Fleur is using as the re-plant happens at the end of the planting loop rather than at the start so the plant is surrounded by two already planted seeds rather than by one. And indeed time is of the essence here, seeds and soil are easilly obtainable (most of them in max 1 hour either by yourself or via retainers) so this this definitelly preferable way of planting as long as there is affordable / "disposable" seed in the loop. This is anyway only valid for planting into completely empty patches as once the loops are running there are usually discrepancies in harverst times so as long as you're keeping the same loop running you'd usually have some plants still in while (re-)planting new seeds in between.