Could you honestly say there are too many daleks in Devious? Or of any TV story? Parting of the Ways sees fleets of them in space whilst Planet of the Daleks is reputed to have the most props in the studio - although the season opener for 2012 will beat that number.
You simply can't have too many! Like Power of the Daleks, Devious only allows a few to be seen at the start. Like Power there is a secret production line and scores are released near the end of the story - we see the threat that a few make and then multiply it. We're only following a tested pattern in expanding the numbers as we reach the climax of the story.
Our largest number on set was nine - or ten if you count the Emperor as well. That was hard enough to co-ordinate. Whilst we had no "dead props" like Death to the Daleks (had 1) we do have moments when our poor tired operators may not have moved enough in some shots, or where we found it difficult to co-ordinate thjeir actiity. At least with a central prop (the control desk) the daleks had a focus for their stick-waving!
Cetainly this did lead to problems with the closing title captions. In our various showings of Devious to friends (we've done this over the years with test versions as it has progressed) we've had opening and closing captions to the six episodes, and by the last 2 parts the number of dalek operators has seemed rather a lot!
Still, we thought that numbers of real daleks would look better than numbers of CGI daleks or models - not that we're not using models and CGI of course.