# How to extend the DefaultDuration of Manipulate[] when it has Bookmarks?

How to extend the DefaultDuration of

Manipulate[x,{x,0,1},Bookmarks->{"beginning":>(x=0),"end":>(x=1)}]

to 20 seconds? I know that DefaultDuration is not an option of Manipulate, but how to do it for Manipulate when it has Bookmarks?

Or, make the x in

Manipulate[x,{x,0,1},AutorunSequencing->{{1,20}}]

changing like 0->1, not like 0->1->0 (due to AutorunSequencing)?

ManipulateDump$DefaultAutorunDuration 4 I would guess that changing the default value of 1.5 to 5 should give 20 seconds duration for the bookmark animation. Row[Labeled[Manipulate[x, {x, 0, 1}, Bookmarks -> {"beginning" :> (x = 0), "end" :> (x = 1)}, Method -> #], #, Top] & /@ {"BookmarkDurationMultiplier" -> .1, "BookmarkDurationMultiplier" -> 3}] Note: I found ManipulateDump$ManipulateMethodOptions through spelunking:
ManipulateDump\$ManipulateMethodOptions