In my own personal experience with DIY...I don't use heat steeping at all. If anything I make
needs to steep to suit my
own tastes (maybe 10% of my eliquids), it does it in its closed bottle, in a cabinet in the house. I'll give it a shake about once a day, but that's it. I'll taste and vape test a few drops about every 3-4 days until it makes my taste buds happy, so to speak, then it's done.
It's a little different though, if a flavoring I used has ethyl alcohol in it. For me, EA
has to be removed before I can vape it, or I'll get a headache almost immediately. So, I shake the heck out of the bottle of my mix, and leave the cap off it, to let all the little bubbles rise to the top and evaporate. Several hours later... I'll shake it vigorously again, creating more bubbles, and leave it uncapped. I do this 3-4 times a day for about 3 days. It's usually a nice, smooth-tasting mix by then, and I get
no headaches vaping it.
Whether you really
need to steep something, or not, is mainly a personal preference, since everyone's taste is different. It sometimes depends on several factors in addition to personal taste, too. The types of flavorings used in them is often a determiner. Most who DIY will agree that eliquids made with tobacco or custard flavorings require steeping of some kind, to be their
best. A second determiner is whether or not the flavorings contain ethyl alcohol. Most agree that it needs to be evaporated off, before you vape the eliquid, not only for better taste, but because EA isn't good for the lungs. Some people who DIY just regularly steep
all eliquids they make. You'd need to get one of them to tell you why though, from their point of view and experience. I can't offer ideas or reasons for that.
One last tip: Don't make DIY any harder nor more expensive for yourself than it needs to be. You don't need to get expensive equipment, gadjets, supplies, etc. to make great eliquids for yourself. Make DIY something you enjoy doing, that saves you money, and allows you to always have eliquids that are custom-made to your liking.
Edit: By the way, if you see later that your discussion has been moved from General Vaping...it's because it's really about DIY E-Liquids. A mod will usually move it there, rather than leave it here.