Two completely opposing views there, that ought to help!
OK, my two cents. I'd recommend neither approach - or both.
When you get to the gym, after some light warmup and gentle stretching, do a pyramid of a single heavy compound free weight exercise. We're talking squats or deads, cleans, something like that. Start relatively light for one set of 12. Bit heavier for 10. Bit heavier again for 8. Now heavy for six, and you need to be pushing like your life depended on it for the last two. Back off and do a set of 12 with the weight you did 10 with. It should be light now!
OK, your body should have gotten a pretty clear message at this point - grow or you're gonna get crushed. Now for the sleight of hand.
Take your target area, your arms. Do pretty much the same thing, but blast them from several angles with isolation exercises. Do 12, 10, 8, 6, 12 sets of one exercise, say barbell curls, and superset that with overhead extensions for the tris. Every session do different isolation moves. The "pyramid" technique isn't so vital here either, 21's work well also. Those are 7 partial reps, say bottom part of curls, then 7 of the upper part, then 7 full range, for 3 or 4 sets. Whatever you do, you are aiming to get a pump and fatigue your arms as quickly as you possibly can. Squeeze and flex every rep.
Then do your cardio and get the hell out. If you've been in the gym longer than 30 mins then you didn't push hard enough on the heavy compound exercise at the start.
The whole idea is to prime the system for growth with the compound exercise and then beat the hell out of the specific bodypart you want to target. It worked for me!
Oh - and training at home. OK, if you have the room and the cash to buy equipment. I did it for years, but spent a fortune turning my garage into a home gym. Squatting 400lbs in an upstairs bedroom isn't recommended. If you're determined you'll find a way. Just be safe! You'd be better off in a gym though. Go in your kit, wear baggies, whatever, you'll be fine.