Safety is paramount in our daily lives. The same applies in the Dojo, perhaps even more so, regarding strict observance of safety in practice. In practice, regardless of Kihon or Waza, gauging of correct distance, correct posture, timeliness of execution, application of force all play a part.
Distance. On some days the Dojo can get rather crowded (a good thing, actually). In such circumstances, it helps to slow down the draws and cuts and pay particular attention to one's surroundings. What happens if one ends up too near the wall, for example, before executing a cut? Rather than just blindly cutting down (thus damaging the wall and iaito), one simply adjust - slow down the cut and make sure not to cut the wall. What happens if both iaidoka comes too close mid-waza? Both acknowledge each other, adjust and give way accordingly. In this way, one practices awareness of the surroundings and of self (Zanshin) and mutual respect. Safety is observed.
Correct posture/ Timeliness of execution. In iaido, wazas are practiced against an imaginary opponent - an image formed in the mind. The real opponent is one's self. Therefore, there's no particular need to rush through a waza - own time, own pace. Far better it is to slow down, observe oneself and the others in executing the waza and try to maintain correct posture. Incorrect posture is a cumulative hazard overtime and it also affects the effectiveness of wazas. Doing a waza slowly creates opportunities for oneself to do self-correction of mistakes mid-waza. In time, the proficiency gained thus paves the way for speed and force. Mindful practice makes perfect.
Application of force. Applying just enough force, at the right place, at the right time, is far better than just brute force. This applies universally be it to kihon or wazas. One prime example is cutting with the iaito or boken. A misleading idea is the more force one applies, the louder the tachikaze. Tachikaze are audible feedback from the iaito/ bokken to the iaidoka in terms of angle of cut (hasuji). Put aside the notion of blindly chasing the tachikaze. Instead think "Correct tenouchi maximises efficiency of the cut" and apply only enough force to do the cut.
So the next time when one does kihon or wazas, don't rush. Observe, learn, improve. Make the best use of practice time.