The telekinesis spells note that if the caster stops concentrating before the duration is up, the object stays in place as if a "staying" spell was in effect. What it doesn't say is whether the caster can stop concentrating, do something, and then resume concentration for a period up to the duration (measured from when the spell was initially cast, I would argue.)
Has anyone considered this, and if so did you allow it or not allow it? I can see both arguments, wondering what kind of trouble it could raise.