I'm a ~1500 rated player on Chess.com's scale (highest rating is 1420 or so, but rapidly growing so we'll say 1500). A few months ago I participated in an invitational tournament against another school's club, and in the month or so beforehand I got Colovic's Short & Sweet Najdorf course on Chessable. I ended up playing 2 games in the Najdorf, both of which I won against some pretty good intermediate players. I ended up winning with a score of 4.5/5.
Recently though I bought Logozar's Najdorf course (also on Chessable) and it has around 150 lines. I don't know how long it would take to complete a course like that, but I'd probably better spend my study time on tactics and strategy. I really like it though, as it has spectacular winning chances for Black and you can really punish your opponent if they don't know what they're doing. If I was higher rated (1700-2000) I would definitely sink the time into learning it.
My question is: how long does it usually take someone to learn a 150-line Chessable course, and is it worth the time to learn an opening I really feel at home in? If not, are there any other defenses against e4 that offer similar themes but are easier to learn/less sharp (i.e. no English Attack)?