I suggest 4-Hour Workweek if you have not come across it already. It looks at everything from a different point of view, i.e. you don't have to try to do as fast as possible, if you don't have to do it at all.

Of course since this is a training requirement, you can also use time management training materials and get your delegates to get exposed to the content.

Hope it helps.

Hello friend,
There are many books on Time management,but by reading only books they will not get full training,they have to do some sort of training, even they can do it for once in a week...
Some book on Time Management are:
1.How To Have A 48-Hour Day(Don Aslett)
2.If You Haven’t Got Time To Do It Right, When Will You Find The Time To Do it over(Jeffrey J.Mayer)
These books are good I read them When I was taking training,suggested by my instructor.

Hello friend,
If your sales representatives don't have time to take classes ..then they can take online help for getting better training on time management..Either they can study through E-books.There are many sites which have a good study material or you can take online Time Management Training Time Management Training..For that also you have many options to choose it from..
So ultimately it depends on the learners choice and their capability because some learners prefer classes while some can acquire knowledge through online training only..So it's depends on them as well as on your budget.

Regards,
Nelson