I have been engaging in powerlifting/weightlifting for over a decade. In my initial years, I was in the "just do weights, don't need cardio" camp. However, around 2018, I started doing cardio mostly to cut body weight as I wanted to hit my personal bests on squats, deadlifts, and bench at a lower body weight.
I personally experienced that my weights moved much better, especially when I was doing more volume work (higher reps) with cardio than without cardio. Cardio seemed to improve my working capacity and I felt more efficient at doing more reps.
So, I would recommend cardio even when one is trying to bulk up in weight and trying to get strong. Doesn't have to be crazy cardio either - just 10 - 15 minutes of zone 2 cardio 4 days a week might be good enough. You can also do types of cardio which work certain muscles - like stair master can be made to specifically target the quads and calves. Or rowing can be good for building the lats. Swimming is good too.
Personally, I either do intervals on the stair master or intervals on an echo bike (fan bike).
I found that cardio tended to severely limit my lifting gains if I did anything more than 30 minutes in a week. I stopped entirely and found my lift increased more rapidly.
But that's just me. Just like all the other variables you have - number of sets, number of repetitions, frequency of workouts, rest periods, it's good to try a few options and see which one your body responds to the best.
One of my few regrets in life, and something I advise to all younger people, is that I didn't work on my upper body strength when I was younger. Now I'm 60, and it's going to be essentially a battle against muscle loss.
So I suppose the message needs to be: Both are important.
60 is plenty young to build muscle as long as you have no serious injuries. You may not be that far off from a 60 year old former college athlete who let it all go to pot at age 35. In fact, I’d wager hardcore 20 something athletes may have experienced injuries that now prevent their older selves from maintaining a healthy lifestyle. There may be advantages to having been a nerdy slight out of shape 30 year old. :)
You can turn weight training into cardio, by keeping breaks between sets down to just a few seconds.
If you go to a fitness center, some have machines set up for this. Mine used to call it circuit training. At home, if you're using free weights, have enough that you don't waste time changing plates.
I see a similar effect too. I usually do just lifting but I recently started doing a bit of cardio (rowing and that resistance treadmill thing) and it improved my lifting even at 5 reps. Granted my cardio was pretty bad but I felt more steady and felt like I could do more volume.
Completely anecdotal but I think cardio of High-Intensity Interval Training (HIIT) type transfers over the best to weight lifting. I am going to guess it has something to do with the intense/explosive intervals in cardio making one more used to similar explosiveness on weights.
Non-intense aerobic exercise exercises a narrower metabolic aspect of your cells than intense anaerobic exercise. You have to be be very careful what you consider is beneficial "cardio".
I have been engaging in powerlifting/weightlifting for over a decade. In my initial years, I was in the "just do weights, don't need cardio" camp. However, around 2018, I started doing cardio mostly to cut body weight as I wanted to hit my personal bests on squats, deadlifts, and bench at a lower body weight.
I personally experienced that my weights moved much better, especially when I was doing more volume work (higher reps) with cardio than without cardio. Cardio seemed to improve my working capacity and I felt more efficient at doing more reps.
So, I would recommend cardio even when one is trying to bulk up in weight and trying to get strong. Doesn't have to be crazy cardio either - just 10 - 15 minutes of zone 2 cardio 4 days a week might be good enough. You can also do types of cardio which work certain muscles - like stair master can be made to specifically target the quads and calves. Or rowing can be good for building the lats. Swimming is good too.
Personally, I either do intervals on the stair master or intervals on an echo bike (fan bike).