So I have tried every method of speed steeping that there is. In my experience, nothing is as good as just letting time have it's way. When I first started DIY I just wanted to have juices I could vape right away, but I love desserts, so I had a conundrum. I used hot water, mixers, lights, etc etc and it does help the mix come together rather than shaking it. So now that I have so much juice I could vape for the next 2 months without making another mix, I have come to find this:
Mixes that I used to put in an overnight hot water bath and vape after a few days ended up sitting for a couple of weeks because I just have so much on hand and like to mix it up. For example a cake batter custard I was vaping after a few days and it was pretty darn good ended up sitting for 2 weeks and holy SH#T it was incredible. 10x better than it was after the hot water bath and a few days. I still do the overnight bath in a giant thermos, it saves me from having to shake the crap out of my stuff and I have a shoulder injury from my baseball days, so shaking 10 mixes for 2minutes each bothers me, but I still let them steep for however much time I think they should. It is just better. It really is.
What I've noticed is this too, flavors that "fade" do fade at a certain point in their steeping process, but they end up coming back to where they should be eventually. So letting things steep their proper amount of time gives you the best final result possible. Some of my juices that I thought were good are now fantastic because they are at their best point.