My therapist allows it, but has quite tight boundaries around it. She will only get back to me on one day of the week between two hours (except she didn't, last time I asked for help). Even before the tighter boundaries, out of session contact was such a bad experience, most of the time. So, I choose not to have any contact between sessions. Previously my therapist ended up annoyed that she felt obliged to reply and apparently the only time she had two minutes to spare would end up being after 10pm. Often she would not get the text and would not get back to me. Took me three years to work up the courage to contact her in between sessions. Totally not worth it!