You'll still have to smooth out the sealant. In case of cracks and holes, first seal the inside area, wait for the sealant to dry, and then seal the outside. Anyway, you'll need to smooth out the sealant and check if the hole is repaired once it's dried, pouring water down the gutter or pipe. Weatherproof adhesive tape is also sometimes a good choice for the cracks in the gutters.
However, you may find it more difficult to seal the area properly compared to using sealant. Apply a generous amount of silicone to the joint and use the nozzle to force it directly into the leak. Once the water has stopped, smooth the silicone flush with the surface. Generally speaking, the interior area of the gutter must first be cleaned to ensure that there is no mold or moss attached to the surface of the gutter.
I suggest using Selley's Grey Storm 290 ml waterproof sealer for gutters and roofs to glue the mini sheet to the surface of the gutter.
