Personally, I have no problem playing up and down the F# arpeggio using side A# - that key just sits naturally under the RH index finger for me.
On the other hand (!) I have to force myself to use the bis key. There are two reasons for this: 1. I started on clarinet which has no bis key; and 2. there is a gap between the B key and the Bb bis key on my Conn tranny tenor which is just wide enough to pinch my index finger. My Conn 10M has less of a gap, but I try and avoid changing fingerings when I change horns.
I genuinely can't understand why so many players consider the bis key a necessity. You have the RH side key, you have two versions of the long Bb: LH1 + RH1 which is good in flat keys and LH1 + RH2 which is good in sharp keys. How many fingerings do you need for Bb? All the same, the bis key is there, so every now and then I deliberately use it, just to remind myself.
Of course there can be a problem with the long Bb which some saxophonists create for themselves by deliberately setting the bis key so that it remains open just a crack when they depress RH1 or RH2. My techy mate does this on his own tenors: he told me it was to make the bis key operate like a third register key, and facilitate some notes in the upper altissimo. He asked me if I wanted him to set up my Conn 10M that way; I refused, because, being a clarinettist, I'm used to the long Bb and want to keep it in good working order, without leaks.