I usually have my charges perform three exercises in a row with no rest between sets, and then have them take a minute off. If there are two leg exercises in the same workout, a longer rest is allowed after the leg exercise in the first grouping. Mixing up your training is helpful and makes exercise fun. It's also plain smart. When you establish certain traditions on certain days of the month or year you really look forward to those special days, and get motivated.
Motivation is the key to training success.
Motivation is also developed by the sandbag and farmer's walk. When you mix it up, remember that this strategy is still part of the overall plan, so it's not haphazard. I'll go two or three weeks and have a planned change of pace day. These days incorporate the same exercises that would have been done on that day, but performed in a different manner to usual-usually fifties day, breakdown fashion, or very slow cadence. Example core program Monday 1.