If you have room in your garden it certainly seems to make sense to have a selection. I have heard that buddleia globosa is good for insects and this is the earliest flowering buddleia that I know of. Again mine is too small for me to really have anything personal of note to report but I hope to in time. I have a buddleia alternafolia which is very pretty with long trailing pannicles of flowers long before the davidiis are in usually in bloom too.
If you prune your buddleias correctly I can see no reason why you shouldn't be able to have them in bloom from late spring until Christmas.
