Without seeing a video, it’s hard to tell. But it’s a common problems others have pointed out in my play, certainly for singles.
If your opponent plays a good quality lift to your forehand corner and you choose to smash straight down the line, you better be sure they cannot play it crosscourt, otherwise it’s the worst shot you can make. If you watch pro games, the response to such a lift/clear is almost always a fast drop down the line, a drop into the centre of the court, or a straight clear. The only time you will see the straight smash is if the opponent is behind in the rally and is stuck in the other ide of the court, unable to defend effectively.
If you smash more often, even if it’s a technically strong stroke, it is suicide when your opponent starts to anticipate it – this is almost certainly the case if your opponent is able to block it crosscourt, making you run he long diagonal.
Playing a neutral, fast drop to the middle or straight means you can recover effectively as you minimise their angles of attack – if you play a effective fast drop, a strong net shot is lap much harder for them, so you won’t need to move s far forward if they choose to play a net shot off your drop.
Finally, a straight clear is used for variation and to keep your opponent back. Think of it like a flick serve – you just want to make sure your opponent is not pushing forward too far, otherwise your drop shots will be less effective.
The above is true do singles, the case for doubles is slightly different. You can choose to straight smash and you should only expect to need to cover the mid court sideline – your partner should cover the net completely. Note that you need to cover the crosscourt lift as well though, so if you feel you can not recover to cover both the straight mid court shot and the lift/drive to backhand corner, you’d be better playing a drop to the middle, or even a smash to the middle (if you hit it straight, you give them more attacking angles)
Hope that makes sense!