I built my first Squirrel model airplane kit recently; previously I had built Squirrels from plans. In the past I thought I could save a little weight and substituted balsa strip that was not as wide. In hindsight, the wood included in the kit will result in a better flying airplane with less chance of warps. The wood quality was good in my kit and all pieces were cut accurately. Not having to cut the pieces is a big issue in many schools because they do not want the students using knives or razor blades.
Test flights were done with hand winds and subsequent flights I used a winder. The rubber strip length included in the kit is just right for hand winds with not too much extra which makes hand winding more difficult. Putting in a fair number of winder turns, the Squirrel climbed quickly to a really good altitude. Normally the glide is not too good which is usually the case with small rubber models when the rubber shifts and the prop starts wind milling in the decent. For the last few flights I switched to 3/32” width rubber and put in a larger number of turns. The plane did not climb as high, but I think the duration was slightly longer, I was not real good on recording data this time. More interested in having fun flying, the geese in the park seemed to be interested in what I was doing also.