First is extremely important that one keeps to the instructions / specification of the manufacturer with regard to the type of application. Of course you need a clean and dry surface to use the tape. In a wet gutter in winter is nothing. Also below 0 ° Celsius, I would not apply.
I have used a plastic downspout including plastic gutter it to mend. After both sites were cleaned and dried the worked just fine, and also holds a few downpours still tight. When used correctly, so it's really waterproof.
Also I have so that the roof patched by a 3x3m gazebo (burn hole of about 1cm) - holds. What has also interesseirt me was whether the tape is actually painted. For although I had no need to have it but simply times on an old wooden frame tries had a crack. Behold, with dark wood varnish which was great to sweep.
At the end of this band is of course only as a substitute for the use case where proper repair for some reason it is not possible or too costly. Wonders one must it not erwartzen, but to have as an additional option for emergencies such a tape in the house, is certainly helpful.
The length of 1.5m, I also think fit (although not cheap). Because you have the tape once opened and in use, the rest of the holding role only conditionally. That means you can store a partially used roll only a limited time in the closet. By the time the tape to lose adhesion.
Generally a great idea.