It seems like my skills decay SO fast!!!!....I don't have very much time to do duolingo, and I like to have my tree golden....so I never advance in my tree, cuz whenever i have a bit of time, i just strengthen skills....not motivating at all!!!why do the skills decay so fast?
Maybe you can strengthen one specific skill? I've never seen my tree non-golden. I start a day on Duolingo getting 100XP+ on Strengthening Skills, then I take one lesson (slow steps), and then, if I just finished a skill with that lesson, strengthen the specific skill once or twice; if I did a lesson which wasn't the skill's last, I just do the regular strengthening skills once or twice, as well.
Around 35 minutes for all of this (with Timed Practice). I also use Memrise for 25 minutes to reinforce my Duolingo knowledge as they have a course with the same Duolingo vocabulary. I also recommend DFE (Deutsch Fuer Euch). Look it up on YouTube and check the description which will lead to the Memrise course of what you learn on DFE (it also includes the videos). At a certain point I will have to practice writing, reading, speaking, listening (I'd say when I'm pretty far into my Duolingo tree).
With only 5 minutes your skills will decay, but you may find yourself eventually better is you apply those 5 minutes instead of doing nothing.
Do you have time (10-20 minutes) to listen to music occasionally? Do you have time (15-30 minutes) to watch a television program or a film? If you do, do it in your target language.