The VHS-Beta format war in the 1970's and 1980's was one reason we ended up with 3 different tape speeds on VHS machines. If you have VHS tapes that need to be transferred to digital files, you should be aware of what you have and at what speed your tape was recorded. Of the 3 speeds that VHS can record, only the standard speed can be played by industrial VHS machines used by the better companies that digitize video tapes.
When designed and introduced by JVC, the VHS format used Standard Play (SP) mode that recorded for 2 hours. Sony's Betamax machines recorded for only 60 minutes when introduced in 1975. Because of the length of football games along with the popular 'Movie of the Week ' and Columbo series that ran 90 minutes, RCA insisted their first branded VCR be capable of longer than 2 hours of recording. Panasonic, a Matsushita company, did a "hack" of the VHS Standard Play mode, reportedly in only 6 weeks, that created the Long Play (LP) mode. RCA introduced a re-branded Panasonic VCR in 1977 with its 4-hour LP mode recording time. Sony rolled out a new Betamax VCR in the same year that had a long play mode but it only recorded up to 2 hours on the L-500 Beta tape.
Long Play mode was not in JVC's specs for the VHS format. Even though JVC and Panasonic were under the same corporate umbrella of Matsushita, JVC was not pleased with Panasonic's alteration. JVC introduced "Extended Play" EP mode to top Panasonic and EP allowed 6-8 hours of recording depending on the tape length used. Panasonic developed the same feature but called it "Super Long Play" or SLP. JVC made sure, at least on early models, that its VCRs would not play LP mode or play it poorly. Later in the VHS life cycle, LP mode was dropped by VCR manufacturers and most later machines only have recording options of SP and EP/SLP mode but will still play an LP-mode tape that was recorded on another VCR.
Consumers using LP and EP settings were simply trying to get more time out of their camcorder or TV recording along with reducing the number of tapes on their shelves. But the main problem with LP and EP/SLP modes is the quality of the recording is simply not very good. Especially on EP/SLP, the video is typically washed out and the audio track quite poor. If you have tapes to transfer and still have a VCR, you can play your tapes to see if the "SP" light or "EP" light is on during playback that indicates what mode was used to record that tape. Sometimes a single VHS tape will have recordings with SP, LP and EP speeds.
For digital transfers on these long play tapes, keep your expectations in check regarding video quality compared to SP mode transfers. Also, make sure your tape transfer service company can handle these longer play VHS modes. There are software enhancements for noise reduction and color correction that can improve these slower speed tape recordings to make the best available conversion of your family movies.