Leisure Stroll for Squirtoria?

It can work pretty good, but since she is already a archer she has pretty high star absorption already so she dosen't need that %400 increase and then there's the case of that if you're running her in the meta comp of tamamo and waver both with 20/30 she has more than enough stars considering caster star weight is low. In my opinion it would be better to run her with another ending or for maximum np spamming formal craft, but if that's all you have it's not a half bad choice :).

What Mcjackingtin said. Generally you wouldn't be running her with dps that would take stars from her. Her best CE for damage is with some ease Black Grail. Formal Craft and Heaven's feel do about as much for her damage as each other. If you have the waver Tamamo setup though heaven's feel is better due to her having no problems charging her np and getting to np more often in general. Another ending is viable if you run double 2030. You may have turns with a star deficit with one or no 2030 though

Yes, Leisure Stroll is decent for Arthuria. But 15% art up means it is a MLB, isn't it?
This CE almost guarantee that Arthuria has almost all star on hand.
Indeed Archer's 150 star adsorption is high versus caster supports and berserkers, but RNG and 90 random star distribution make it sill possible that your supports could adsorb amount of star rather than Arthuria.
Also with this CE, you can build a critical team more flexible, like use Mashu as defensive support, or David as demi-support, or using assassin like Jack, MHX, Shishou, Fumma or Kiritsugu as star generator/demi-support.

Off course, the major configuration is still Arturia + Tamamo + Tamamo/Waver/Hans. Arthuria can bring any art-up CE or black grail if your Arthuria's NP>=2
.