I have been completing my daily classes on the French course for months now. I spend about half an hour every day. I understand the need to revise lessons often but almost all of the lessons right back to basics loose their golden colour every day. This is most disheartening. I feel I can't make any progress.. I also paid a while ago to repair my streak. This had no effect so I don't know why you ask people to do it. Thinking of giving up.
You do not necessarily have to strengthen something just because it is not gold, if you feel that you know that skill very well then leave it and move onto something you feel you do not know well, even if it's gold. The algorithm is based off of averages of how much time passes before you forget a word, Duolingo follows this average so makes the skills non gold based on averages of when people will have forgotten. However with averages there is always a lot of people who do not fit into that and so this method will not work for them, it is fairly likely that you are one of these people so if it helps you to not follow Duolingos algorithm then you should do that and focus on the ones you know you need to improve on.