Isn't it funny how we get contradicting reports!
I occasionally put a clothes peg on mine to hold the switch down (mine is mounted on the scope) and use it for pointing out objects to which the people can look in the scope and see what its pointing at. I leave it switched on by clothes peg for up to 5 mins or more with no dramas. I am still using the same energisers I put in it about 12 months ago. And I use it a lot! Just ask the folks from Camp!
Last month I used it handheld at the SVAA club night to show members and visitors all over the sky and it was on for long periods. Later in the night I used it for Eric to point his scope where it was pointing to find the Leo Galaxies, and it was on for long periods then too.