Re: Hi, New member, looking to lean up and get stronger with less gym time :D
How many days you train is largely irrelevant. It's the intensity and amount of training that counts. Many fall into the trap on what the bodybuilding mags and such put out with routines that may suit a guy on steroids and with great genetics but are unrealistic for the average natty guy. Many who workout do more than they actually need to, fannying about with multiple exercises and sets per bodypart that are far from optimal, though some enjoy being in the gym for hours on end.
The basic compound exercises along with isolation exercises (for arms) and a good diet and rest are all most require to put on a decent bit of muscle, though some unlucky blokes (the ectomorph types) will struggle no matter what they do.
At 31 your T levels will not have dropped by much at all, though maybe you've always had low(ish) T levels. If you feel you're not recovering it may be down to overtraining and/or diet and rest. If you do go down the dark side then 250mg of testosterone per week for 10 to 12 weeks would be all you need for a first cycle and some Nolvadex for post cycle recovery.