We are going to start with the least glamorous part of the gameplan while on court, defending. A large portion of your time on court will be spent in positions on the court that are relatively far from your ideal 'T' position. As a consequence, you will need more time after playing your shot to recover and get into a better position. Additionally, by the time you have moved from the 'T' to these locations to play the ball your opponent has had time themselves to recover and will likely have the 'T' position that you've just vacated. If this is the case (they are on the 'T'), your shot choice must be one that allows you time and space to take the 'T' back off your opponent. The 4 corners of the court should be considered defensive areas, as long as you have no information that your opponent is out of position.
Have a think about the pros and cons of each potential shot choice from these defensive areas to determine what shot you should play. Will you be able to get to the 'T' before your opponent plays their shot? Will you be in danger of interfering with your opponents next shot? Does your shot have to be great or just good quality in order to recover? Is your shot predicatable, allowing your opponent to be away from the 'T' without consequence? In the writing below, I will go over some brief pros and cons of some shot choices from the defensive areas.
The lob is an often underutilised shot that is utterly crucial if you plan on making it back to the 'T' consistently. When played from the front of the court it is hands-down the best option for giving yourself time to recover back to the 'T'. Better yet, even less-than-good quality lobs will often still give you adequate time to recover, at least somewhat! From the back of the court, the benefits are similar, with shots making use of the ample space above a court, giving you both time and the ability to keep the ball out of reach of your opponent.
When choosing between a straight and cross-court lob, it is important to consider a few points. Firstly, a cross court lob makes use of the height above the court away from the side wall out lines, which are always a risk when hitting straight. Secondly, hitting cross-court moves your opponent to the side of the court opposite to you, removing much of the risk of interference between players which can occur for many other shots including a poorly executed straight lob from the front of the court (though still better than a hard hit straight drive).
The cons of these choices include the aforementioned risk of hitting the ball out, as well as the lower likelihood of hitting an outright winner. The last point, however, I wouldn't really consider a con as the likelihood of hitting winners off other shot choices from these defensive positions decreases considerably with increasing skill levels.