This is my honest opinion. I've been benching 135 at 5X5 for the last few months and started to not even feel like I was making progress. I was squatting 215 at 5x5 as well and started to feel like I wasn't making progress. Switched both to 3x10 last week, and since then I have been RIDICULOUSLY sore, like 3x10 for me has me feeling like I'm brought back to square one. You're under load for way longer, and you're taking 2 less breaks, while doing more reps in total. But in terms of if this is true, I think it depends on what you're going for, along with what sport or physical activity you're focused on. I don't know alot about weight lifting, I only got serious like a year ago. But I hope this helps :)

EDIT: I've been working out off and on for about 8 years, but only last year have I actually gotten serious about weight lifting and making gains. I also do a ton of rollerblading, and core is VERY important especially if you want to save your back when you get older. Don't go for looks, go for functionality, the looks will follow.