I'm a fan of intentional design. While I know not every situation can be planned for, especially in a tabletop game where the players are apt to surprise you, I like to have intricate encounters that I know my players will face prepared ahead of time. However, I suck at creating those encounters in a timely manner.
I don't like just copy-pasting a bunch of vanilla baddies onto the field and rolling attack rolls until one side drops. When I design an encounter, I usually build it with the roles of a standard adventuring party in mind unless it wouldn't make sense to do so. I also like to include environmental hazards and options to keep the field dynamic. And if I get the inspiration, I'll include a unique mechanic or objective to make the encounter more memorable and exciting.
This all works particularly well for me in the end result, but getting there is a slog. I can spend hours, even days designing only a small handful of encounters, and it's very time-consuming.
Any tips or tools to speed up the process? I'm GMing over Roll20 and am very familiar and proficient with the tools it has to offer already. Mostly, I think my design process is too scattered, but I'm not sure how to reel it in.
I don't know how intensive you're going, but you can always skip a couple steps. For example, it's not really important to the encounter if one of the barbarians has three ranks in knowledge (local). There is also the beautiful gift of reflavoring. You don't have to make a different kind of fighter every time, your players won't notice if you copy the stats and just have it be a human instead of a half-orc.